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Displaying status and statistics: Dell OpenManage™ Data Supervisor, Event Monitor, and Integrator Installation and Operation Guide

Overview • About statistics logging • Array Information window • SP Information window • LUN Information window • Disk Information window

Overview

This chapter describes how to display all the information windows that provide status and statistics about an array, SP, LUN, disk module, or caching. It also describes how to turn on and off the statistics log that supplies the information for these windows. For information on how to display and save the event log for an SP, see "Opening the Event Log window".

Many of these windows display statistics. Normally, statistics are not logged, since logging it may affect performance. For meaningful statistics, you must enable statistics logging as explained in the next section. If statistics logging is already enabled or you do not care about statistics, continue to the section listed below for the information you want.

About statistics logging

Each SP maintains a log of statistics for the LUNs, disk modules, and array caching that you can turn on and off. When statistics logging is on, it affects array performance, so you may want to leave it off unless you have a reason to monitor performance.

The statistics log uses a 32-bit counter to maintain the statistics numbers, so when the counter is full, the statistics numbers restart at zero. As a result, you will see a sudden decrease in a statistics number if you view it shortly before the counter is full and shortly after the counter restarts at zero. If you want to keep the log turned on for more than two weeks, we recommend that you reset the log about every two weeks, so you know when the numbers start at zero.

To turn SP statistics logging on and off

1. Display the Array Configuration window (see "To display the Array Configuration window").
2. In the Array Configuration window, select the menu option Array � Statistics Logging State.
3. Select the SP whose statistics logging state you want to change.

A confirmation window opens.

4. In the confirmation window, click Yes to confirm the change in the statistics logging state for the SP, or click No to leave the state unchanged.

An information window opens saying that statistics logging was successfully enabled or disabled for the selected SP.

5. In the information window, click the OK button.

To change the statistics logging state of the other SP, repeat step 2 through step 5.

To reset the statistics log for an SP

1. Display the Array Configuration window (see "To display the Array Configuration window").
2. In the Array Configuration window, select the menu option Array � Reset Statistics Logging.
3. Select the SP whose statistics log you want to reset.
4. A confirmation window opens.
5. In the confirmation window, click Yes to reset the statistics log for the SP.

An information window opens saying that statistics logging was successfully reset for the SP.

6. In the information window, click the OK button.

To reset the statistics log for the other SP, repeat step 2 through step 5.

Array Information window

The Array Information window displays configuration information for the array.

Displaying array configuration information

To display array configuration information

1. In the Components, Array Configuration, or Equipment View window, either click the Array Information button on the toolbar or select the menu option Array � Information.

An Array Information window for the selected array opens, similar to the sample that follows.

Figure 9-1. Sample Array Information window

State - Current operating state of the array. An array can be in any of these states:

Automatic Polling Priority - Always 1. You cannot change this value or the automatic polling interval, which is always 60 seconds. As a result, when automatic polling is enabled, Data Supervisor automatically polls Data Agent for information on the array every 60 seconds. The automatic polling interval has no effect on manual polling.

When Data Supervisor polls, it retrieves information about array status changes from Data Agent, and updates the status information for the array in any open window. An automatic poll of an array functions the same way as a manual poll of the array.

For information on when Data Agent polls arrays and when Data Agent responds to polls from Data Supervisor, see "Automatic and manual polling for managed array information".

Automatic Polling Count - 0 or 1. If it is 0, Data Supervisor just polled Data Agent for array status information. If it is 1, Data Supervisor will poll Data Agent when one polling cycle elapses.

Automatic Disk Formatting - Enabled, Disabled, or Not Applicable. When automatic disk formatting is enabled the SP's Licensed Internal Code (LIC) automatically formats any disk module that has an unrecognizable format. If an array does not support automatic disk formatting, this field contains Not Applicable. In arrays that support automatic disk formatting, the LIC sets the state of the automatic disk formatting parameter, and you cannot change it with Data Supervisor.

Disk Write Caching - Enabled, Disabled, or Not Applicable. When enabled, disk write caching is enabled for the array. For arrays that do not support disk write caching, this field contains Not Applicable. For arrays that support disk write caching, the disk write caching state is set by the SP's LIC, and you cannot change it with Data Supervisor.

RAID 3 Write Buffering - Enabled, Disabled, or Not Applicable. By default, RAID 3 write buffering is disabled for an array that supports it.

NOTE: Do not enabled it because using RAID 3 write buffering may result in data loss and the design of the SP makes it unnecessary.

Mixed Mode - Enabled, Disabled, or Not Applicable. By default mixed mode is enabled for an array, and it must remain enabled if the array has any LUN that is not a RAID 3 LUN or a hot spare. If it is disabled, it optimizes the SPs for RAID 3 transfers. You can change the Mixed Mode state from the Array Configuration window by selecting whichever of the following menu options appears:

Array � Disable Mixed Mode

Array � Enable Mixed Mode

Host Connection - Each physical connection to the array's server. A connection has the following format:

hostname, device, SP

where

For an array with two SPs, a host connection to each SP is required to provide information on each SP.

SP Information window

The SP Information window displays either configuration, statistics, or cache information for the SP. The window has a round view button for selecting each type of information. The view button with the dot indicates the type of information displayed.

Displaying SP configuration information

To display SP configuration information when the SP Information window is open

If the SP Information window is not displaying configuration information, click the Configuration view button.

SP configuration information is displayed in the SP Information window, similar to that in the sample that follows.

To open the SP Information window and display SP configuration information

1. Display the Array Configuration window (see "To display the Array Configuration window").
2. In the Array Configuration window, either click the SP A or SP B Information button on the array toolbar or follow one of these menu paths: Array � SP Information � SPA or Array � SP Information � SPB.

An SP Information window with configuration information opens, similar to that in the sample that follows.

Figure 9-2. Sample SP Information window with configuration information

State - Current operating state of the SP. An SP can be in any of these states:

Firmware Revision - The revision of the Licensed Internal Code (LIC) that the SP is running. Each SP in the array will be running the same revision of LIC. You can update an SP's LIC as described in the "Updating Licensed Internal Code (LIC) and PROM code".

NOTE: If the Firmware Revision field and/or the PROM Revision field are zero or blank, the host connection is missing or invalid.

PROM Revision - The revision of the SP's PROM code. Each SP in the array will be running the same revision of PROM code. PROM code is updated automatically when you update an SP's LIC as described in "Updating Licensed Internal Code (LIC) and PROM code".

Model - The product model number for the SP.

Date and Time - The system time for the SP, which Data Agent sets to the server time when it is started. This time is updated only when the SP on the array is polled.

Total Read Cache Memory - The size in Mbytes of the SP's array read cache partition. For information on how to change the size of the read cache memory partition, see "Setting up or changing array memory partitions".

Total Write Cache Memory - The size in Mbytes of the array write cache partition. For information on how to change the size of the write cache memory partition, see "Setting up or changing array memory partitions".

Total Memory - The size in Mbytes of the SP's physical memory. Each SP in an array must have the same amount of memory to make full use of the memory.

Data Loop Fail-Over - Current operating state of the SP's back-end data loop. The back-end data loop can have any of these states:

Command Loop Fail-Over - Current operating state of the SP's back-end command loop. The back-end command loop can have any of these states:

Illegal Cross Loop - Indicates whether the enclosures in an array have been incorrectly cabled so that the back-end Fibre Channel loops are crossed. This field can have these values:

This field is True when an LCC A in the array is connected to an LCC B in the array.

Enclosure Cabling Order - Lists the enclosure addresses (EAs) for all enclosures in the array in the order in which they are cabled together. DPEs always have an EA of 0. For example, if the Enclosure Cabling Order field contains 0, 1, 3, it means that the array's DPE (enclosure 0) is cabled to a DAE with an EA of 1 (enclosure 1); enclosure 1 is cabled to another DAE with an EA of 3 (enclosure 3).

Displaying SP statistics

NOTE: If statistics logging for the SP is not enabled, the statistics displayed in the SP Information window are not updated when Data Supervisor polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display SP statistics when the SP Information window is open

If the SP Information window is not displaying statistics, click the Statistics view button.

SP statistics are displayed in the SP Information window, similar to that in the sample that follows.

To open the SP Information window and display SP statistics

1. Display the Array Configuration window (see "To display the Array Configuration window").
2. In the Array Configuration window, either click the SP A or SP B Information button on the array toolbar or follow one of these menu paths: Array � SP Information � SPA or Array � SP Information � SPB.

An SP Information window opens.

3. In the SP Information window, click the Statistics view button.

SP statistics are displayed in the SP Information window, similar to that in the sample that follows.

Figure 9-3. Sample SP Information window with statistics

Statistics Logging - Enabled if SP statistics logging is enabled (see above); Disabled if statistics logging is disabled.

Number of Reads - Total number of read requests made to the SP.

Number of Writes - Total number of write requests made to the SP.

Number of Blocks Read - Total number of 512-byte data blocks read from the SP.

Number of Blocks Written - Total number of 512-byte data blocks written to the SP.

Percent Busy - The percentage of time that the SP was busy (processing requests) and not idle. The number shows the relative load on the SP.

Displaying SP cache information

NOTE: If statistics logging for the SP is not enabled, the cache statistics displayed in the SP Information window are not updated when Data Supervisor polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display SP cache information when the SP Information window is open

If the SP Information window is not displaying cache information, click the Cache view button.

SP cache information is displayed in the SP Information window, similar to that in the sample that follows.

To open the SP Information window and display SP cache information

1. Display the Array Configuration window (see "To display the Array Configuration window".
2. In the Array Configuration window, either click the SP A or SP B Information button on the array toolbar or follow one of these menu paths: Array � SP Information � SPA or Array � SP Information � SPB.

An SP Information window opens.

3. In the SP Information window, click the Cache view button

SP cache information is displayed in the SP Information window, similar to that in the sample that follows.

Figure 9-4. Sample SP Information window with cache information

Read Cache State - Current state of the array read cache for the SP. The array read cache states are Enabled, Disabling, and Disabled. For information on enabling and disabling the array read cache, see "Enabling or disabling array caching".

Read Cache Size - The amount of memory, in Mbytes, allocated to this SP's read cache partition.

Read Cache Hit Ratio - The percentage of read requests to an SP that were hits for the SP's read cache. A read cache hit occurs when the SP finds a sought page in read cache memory, and thus does not need to read the page from disk.

Write Cache State - Current state of the array write cache. The array write cache states are Enabled or Disabled, and transition states, such as Initializing, Syncing, Enabling, Quiescing, Disabling, Dumping, and Frozen. For information on enabling and disabling the array write cache, see "Enabling or disabling array caching".

Write Cache Size - The amount of memory, in Mbytes, allocated to this SP's write cache partition.

Write Cache Hit Ratio - The percentage of write requests to an SP that were hits for the SP's write cache. A write cache hit occurs when the SP finds and modifies data in the write cache memory, which usually saves a write operation. For example, a hit that occurs when a page is sought in a RAID 5 LUN eliminates the need to read, modify, and write the data. High ratios are desirable because each hit indicates at least one disk access that was not needed.

Write Cache Type - Mirrored or non-mirrored.

Page Size - The size of a page in Kbytes (KB) in the SP's read or write cache.

Number of Pages - The total number of write cache pages currently owned by the SP.

Number of Unassigned Pages - The number of write cache pages that are not currently owned by the SP.

Percentage of Dirty Pages - The percentage of the write cache pages owned by the SP that have been modified since they were last written to disk. A high percentage of dirty pages means the write cache is handling many write requests.

LUN Information window

The LUN Information window displays either configuration, statistics, or cache information for the LUN. The window has a round view button for selecting each type of information. The view button with the dot indicates the type of information displayed.

Displaying LUN configuration information

To display LUN configuration information when the LUN Information window is open

If the LUN Information window is not displaying configuration information, click the Configuration view button.

LUN configuration information is displayed in the LUN Information window, similar to that in the sample that follows.

To open the LUN Information window and display LUN configuration information

1. Display the Array Configuration window for the array with the LUN whose configuration information you require (see "To display the Array Configuration window").
2. In the Array Configuration window, double-click the LUN whose configuration information you require.

NOTE: You can open the LUN Information windows with configuration information for multiple LUNs by selecting the icons for the LUNs and then using either the LUN Configuration Information button on the LUN toolbar or the menu option LUN � Display Information � Configuration.

A LUN Information window with configuration information opens, similar to that in the sample that follows.

Figure 9-5. Sample LUN Information window with configuration information

RAID Type - The RAID type of the LUN. Available RAID types are

Element Size - Number of sectors that the array can read or write to a single disk module in the LUN without requiring access to another disk module in the LUN. For a RAID 5, RAID 0, and RAID 1/0 LUN the default stripe element size is 128 sectors, and the size is specified when the LUN is bound. For a RAID 3 LUN the default stripe element size is fixed at 1. The element size was set when you created the LUN and you cannot change it without unbinding and rebinding the LUN.

NOTE: The Element Size field contains Not Applicable for RAID 1 LUNs, Disk LUNs, or hot spares.

Rebuild Time - Maximum number of hours that the array can take to integrate a hot spare or new disk module into the LUN. The default rebuild time of 4 hours is adequate for most applications. A rebuild time of 2 hours rebuilds the disk module more quickly, but degrades response time slightly. A rebuild time of ASAP rebuilds the disk module as soon as possible, but degrades the response time significantly.

The rebuild time was set when the LUN was bound. You can change it at any time (as described in the section starting in "Changing any LUN parameter except for the default SP and prefetch parameters") without affecting the data on the LUN.

NOTE: The Rebuild Time field contains Not Applicable for RAID 0 LUNs, Disk LUNs, or hot spares.

Verify Time - Amount of time that the array allots to checking parity. If an SP detects parity inconsistencies, it starts a background process to check all the parity sectors in the LUN. The time you specify determines the amount of resource the SP devotes to verifying instead of to normal I/O activity. The default verify time of 4 hours is adequate for most applications. A verify time of 2 hours checks parity more quickly, but degrades response time slightly. A verify time of ASAP checks parity as soon as possible, but degrades the response time significantly.

The verify time was set when the LUN was bound. You can change it at any time (as described in the section starting in "Changing any LUN parameter except for the default SP and prefetch parameters") without affecting the data on the LUN.

NOTE: The Verify Time field contains Not Applicable for RAID 0 LUNs, Disk LUNs, or hot spares.

Default SP - SP that takes ownership of the LUN when the array is powered up. The default SP was set when you bound the LUN. You can change it at any time (as described in the section starting in "Transferring default ownership of a LUN from one SP to another") without affecting the data on the LUN.

NOTE: The Default SP field contains Not Applicable for hot spares.

Auto Assignment State - Enabled or Disabled. The original default is Disabled. Auto assignment controls the ownership of a LUN when an SP fails in an array with two SPs. With auto assignment enabled, if the SP that owns a LUN fails and the server tries to access that LUN through the second SP, the second SP assumes ownership of the LUN so the access can occur. The second SP continues to own the LUN until the failed SP is replaced and the array is turned off and then on again. Then ownership of each LUN returns to its default SP. If auto assignment is disabled in the previous situation, the second SP does not assume ownership of the LUN, so the access to the LUN does not occur.

Auto assignment was set when the LUN was bound. You can change it at any time (as described in the section starting in "Changing any LUN parameter except for the default SP and prefetch parameters") without affecting the data on the LUN.

NOTE: The Auto Assignment State field contains Not Applicable for hot spares or any LUNs in an array with only one SP.

Minimal Latency Reads State - Enabled or Disabled. Minimal latency reads provide a more constant bandwidth between the SP and the server when the bandwidth between the disk modules in a RAID 3 LUN and the SP decreases because of a slow response from a disk module. Minimal latency reads change how the SP responds to a request from the server to read a RAID 3 LUN.

When the minimal latency reads state is disabled, the SP does not perform minimal latency reads to the LUN, and thus degrades system throughput. When the minimal latency reads state is enabled, the SP performs minimal latency reads to the LUN, thus improving system throughput.

You can change the minimal latency reads state You can change it at any time (as described in the section starting in "Changing any LUN parameter except for the default SP and prefetch parameters") without affecting the data on the LUN.

NOTE: The Minimal Latency Reads State field contains Not Applicable for any LUN other than a RAID 3 LUN.

Disks - Disk IDs of the modules that make up the LUN. A disk ID is the enclosure address (EA) of the chassis containing the disk multiplied by 10 plus the number of the slot (0 through 9) containing the disk. For example, 00 - 04 means that the LUN consists of disk modules in slots 0 through 4 in enclosure 0. The disk modules that make up a LUN are set when the LUN was bound. You cannot change them without unbinding and rebinding the LUN. The EA is set with switches on the chassis.

Percent Rebuilt - If less than 100%, indicates that a disk in the LUN is being rebuilt and shows the percentage of the rebuild completed.

Percent Bound - If less than 100%, indicates that the LUN is being bound and shows the percentage of the bind completed.

Hot Spare Replaces - If the LUN is a hot spare that is replacing or has replaced a faulty disk module in another LUN, this field lists the other LUN and its faulty disk module. If the LUN is a hot spare that is not being used, this field contains Inactive.

NOTE: This field is displayed only if the LUN is a hot spare.

Displaying LUN statistics

NOTE: If statistics logging for the SP is not enabled, the LUN statistics displayed in the SP Information window are not updated when Data Administrator polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display LUN statistics when the LUN Information window is open

If the LUN Information window is not displaying statistics, click the Statistics view button.

LUN statistics are displayed in the LUN Information window, similar to that in the sample that follows.

To open the LUN Information window and display LUN statistics

1. Display the Array Configuration window for the array with the LUN whose statistics you require (see "To display the Array Configuration window").
2. In the Array Configuration window, double-click the LUN whose statistics you require.




NOTE: You can open the LUN Information windows with statistics for multiple LUNs by selecting the icons for the LUNs and then using either the LUN Statistics Information button on the LUN toolbar or the menu option LUN � Display Information � Statistics.

A LUN Information window opens.

3. If the LUN Information is not displaying statistics, click the Statistics view button.

LUN statistics are displayed in the LUN Information window, similar to that in the sample that follows.

Figure 9-6. Sample LUN Information window with statistics

Number of Reads - Total number of read requests made to the LUN.

Number of Writes - Total number of write requests made to the LUN.

Number of Blocks Read - Total number of 512-byte data blocks written to the LUN.

Number of Blocks Written - Total number of 512-byte data blocks written to the LUN.

Number of Stripe Crossings - Total number of times that a read or write crosses a stripe boundary on any disk module in a RAID 5, RAID 1/0 or RAID 0 LUN. Generally stripe crossings are undesirable, since each one requires an additional I/O. As a general guideline, the ideal stripe element size is the smallest size that does not cause an additional I/O to another disk module. From the displayed number of crossings, you can determine the percentage of I/Os that required a stripe boundary crossing as follows: add the number of reads to the number of writes, and divide the number of crossings by this sum. A relatively low percentage indicates a relatively efficient stripe element size.

Display LUN cache information

NOTE: If statistics logging for the SP is not enabled, the LUN cache information displayed in the SP Information window is not updated when Data Administrator polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display LUN cache information when the LUN Information window is open

If the LUN Information window is not displaying cache information, click the Cache view button.

LUN cache information is displayed in the LUN Information window, similar to that in the sample that follows.

To open the LUN Information window and display LUN cache information

1. Display the Array Configuration window for the array with the LUN whose statistics you require (see "To display the Array Configuration window").
2. In the Array Configuration window, double-click the LUN whose statistics you require.




NOTE: You can open the LUN Information windows with statistics for multiple LUNs by selecting the icons for the LUNs and then using either the LUN Cache Information button on the LUN toolbar or the menu option LUN � Display Information � Cache.

A LUN Information window opens.

3. If the LUN Information is not displaying cache information, click the Cache view button.

LUN cache information is displayed in the LUN Information window, similar to that in the sample that follows.

Figure 9-7. Sample LUN Information window with cache information

Read Cache State - Enabled or Disabled for this LUN. For read caching to occur with this LUN, the array read cache must be enabled for the SP owning the LUN. The cache view of the SP Information window ("Displaying SP cache information") tells you if this cache is enabled. For information on enabling and disabling the array read cache for an SP, see "Enabling or disabling array caching".

NOTE: The Read Cache State field contains Not Applicable for RAID 3 LUNs or hot spares.

Write Cache State - Enabled or Disabled for this LUN. For write caching to occur with this LUN, the array write cache must be enabled. The cache view of the SP Information window ("Displaying SP cache information") tells you if this cache is enabled. For information on enabling and disabling the array write cache, see "Enabling or disabling array caching".

NOTE: The Write Cache State field contains Not Applicable for RAID 3 LUNs or hot spares.

Read Cache Hit Ratio - The percentage of cache read hits for the LUN. A read hit occurs when the SP finds a sought page in cache memory, and thus does not need to read the page from disk. A High hit ratio is desirable because each hit indicates at least one disk access that was not needed. You may want to compare the read hit ratio for the LUN with the read hit ratio for the entire array in an SP Cache window ("Sample SP Information window with cache information"). For a LUN to have the best performance, the hit ratio should be higher than that for the array. A very low read hit ratio for a busy LUN may mean that caching is not helping the LUN's performance.

NOTE: The Read Cache Hit Ratio field contains Not Applicable for RAID 3 LUNs or hot spares.

Write Cache Hit Ratio - The percentage of cache write hits for the LUN. A write hit occurs when the SP finds and modifies data in cache memory, which usually saves a write operation. For example, with a RAID 5 LUN, a write hit eliminates the need to read, modify, and write the data. A high hit ratio is desirable because each hit indicates at least one disk access that was not needed. You may want to compare the write hit ratio for the LUN with the write hit ratio for the entire array in an SP Cache window ("Sample SP Information window with cache information"). For a LUN to have the best performance, the hit ratio should be higher than that for the array. A very low write hit ratio for a busy LUN may mean that caching is not helping the LUN's performance.

NOTE: The Write Cache Hit Ratio field contains Not Applicable for RAID 3 LUNs or hot spares.

Number of Blocks Prefetched - Number of disk blocks (512-bytes) prefetched for the LUN when prefetching is enabled for the LUN. Prefetching is read-ahead caching. It lets the SP anticipate the data an application will request so that it can read it from disk into its read cache before the data is needed. When prefetching is enabled, the SP monitors I/O requests to each LUN for sequential reads, and if any occur, it prefetches data from the LUN.

The Number of Blocks Prefetched field and the next field indicate how well (how often) prefetching is working for this LUN.

NOTE: The Number of Blocks Prefetched field contains Not Applicable for RAID 3 LUNs or hot spares.

Number of Unused Prefetched Blocks - Number of 512-byte disk blocks that were prefetched but not used. Prefetching is read-ahead caching. It lets the SP anticipate the data that an application will request so that it can read it from disk into its read cache before the data is needed. When prefetching is enabled, the SP monitors I/O requests to each LUN for sequential reads, and if any occur, it prefetches data from the LUN. A higher number may mean that prefetching is not an efficient choice for this LUN.

NOTE: The Number of Unused Prefetched Blocks field contains Not Applicable for RAID 3 LUNs or hot spares.

Number of Forced Flushes - Number of times the write cache was flushed to make room in the write cache for a write request (because the cache filled to its high-water mark). A higher number is not desirable because a forced flush suspends all other I/O.

NOTE: The Number of Forced Flushes field contains Not Applicable for RAID 3 LUNs or hot spares.

Disk Information window

The Disk Information window displays either configuration, statistics, or error information for the disk module. The window has a round view button for selecting each type of information. The view button with the dot indicates the type of information displayed.

Displaying disk configuration information

To display the disk configuration information

1. Display the Array Configuration window for the array with the disk module whose configuration information you require (see "To display the Array Configuration window").
2. In the Disk Field, double-click the disk module whose configuration information you require.

The Disk Information window with configuration information opens, similar to that in the sample that follows.

Figure 9-8. Sample Disk Information window with configuration information

Capacity - Storage capacity of the disk module in Mbytes (MB).

State - Current operational state of the disk module. A disk module can be in any of the states in the table that follows.

LUN ID - Hexadecimal number identifying the LUN to which the disk module is bound. You specified this number in the Bind window when you bound the LUN.

NOTE: The LUN ID field contains Not Applicable when the disk module is not bound into a LUN.

LUN Type - The RAID type of the LUN to which the disk module is bound. You specified this type in the Bind window when you bound the LUN. Available RAID types are

NOTE: The LUN Type field contains Not Applicable when the disk module is not bound into a LUN.

Hot Spare Replaces - If the disk module is a hot spare that is replacing or has replaced a faulty disk module in another LUN, this field lists the other LUN and its faulty disk module. If the disk module is a hot spare that is not being used, this field contains Inactive.

NOTE: This field is displayed only if the disk module is a hot spare.

User Sectors - The number of user-accessible 512-byte sectors on the disk module.

Displaying disk statistics

NOTE: If statistics logging for the SP is not enabled, the disk statistics displayed in the Disk Information window is not updated when Data Administrator polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display disk statistics when the Disk Information window is open

If the Disk Information window is not displaying statistics, click the Statistics view button.

Disk statistics are displayed in the Disk Information window, similar to that in the sample that follows.

To open the Disk Information window and display disk statistics

1. Display the Array Configuration window for the array with the disk module whose statistics you require (see "To display the Array Configuration window").
2. In the Disk Field, double-click the disk module whose statistics you require.

The Disk Information window opens.

3. In the Disk Information window, click the Statistics button.

Disk statistics are displayed in the Disk Information window, similar to that in the sample that follows.

Figure 9-9. Sample Disk Information window with statistics



Average Disk Request Service Time - Average amount of time in milliseconds that the disk module required to execute an I/O request after the request reached the top of the queue.

Number of Reads - Total number of read requests made to the disk module. You might find the LUN read information displayed in the LUN Statistics ("Displaying LUN statistics") more useful because it is for the entire LUN, and not just for one of the disk modules in the LUN.

Number of Writes - Total number of write requests made to the disk module. You might find the LUN write information displayed in the LUN Statistics ("Displaying LUN statistics") more useful because it is for the entire LUN, and not just for one of the disk modules in the LUN.

Number of Blocks Read - Total number of 512-byte data blocks read from the disk module.

Number of Blocks Written - Total number of 512-byte data blocks written to the disk module.

Number of Read Retries - Total number of times read requests to the disk module were retried because of soft or hard errors. The error view of the Disk Information window displays hard and soft read errors ("Displaying disk error information").

Number of Write Retries - Total number of times write requests to the disk module were retried because of soft or hard errors. The error view of the Disk Information window displays hard and soft write errors ("Displaying disk error information").

Displaying disk error information

NOTE: If statistics logging for the SP is not enabled, the disk error information displayed in the Disk Information window is not updated when Data Administrator polls for array information. To enable statistic logging for the SP, see "To turn SP statistics logging on and off".

To display disk error information when the Disk Information window is open

If the Disk Information window is not displaying error information, click th displaying error information, click the Error view button.

Disk error information is displayed in the Disk Information window, similar to that in the sample that follows.

To open the Disk Information window and display the disk error information

1. Display the Array Configuration window for the array with the disk module whose error information you require (see "To display the Array Configuration window").
2. In the Disk Field, double-click the disk module you require.

The Disk Information window opens.

3. In the Disk Information window, click the Errors button.

The Disk Information window with error information opens, similar to that in the sample that follows.

Figure 9-10. Sample Disk Information window with error information

Number of Hard Read Errors - Total number of read errors for the disk module that persisted through all the retries. An increasing number of hard errors may mean that the disk module is nearing the end of its useful life.

Number of Hard Write Errors - Total number of write errors for the disk module that persisted through all the retries. An increasing number of hard errors may mean that the disk module is nearing the end of its useful life.

Number of Soft Read Errors - Total number of read errors for the disk module that disappeared before all the retries. An increasing number of soft errors may indicate that the disk module is nearing the end of its useful life.

Number of Soft Write Errors - Total number of write errors for the disk module that disappeared before all the retries. An increasing number of soft errors may indicate that the disk module is nearing the end of its useful life.

Number of Remapped Sectors - Total number of disk sectors on the disk module that were faulty when written to, and thus were remapped to different parts of the disk module.

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