Dell PowerVault MD 32XX/36XX Series Storage Arrays CLI Guide

Set Virtual Disk Attributes For A Disk Pool

Description

This command defines the properties for a virtual disk. You can use most parameters to define properties for one or more virtual disks. You also can use some parameters to define properties for only one virtual disk. The syntax definitions are separated to show which parameters apply to several virtual disks and which apply to only one virtual disk. Also, the syntax for virtual disk mapping is listed separately.

NOTE: In configurations where disk groups consist of more than 32 virtual disks, the operation can result in host I/O errors or internal RAID controller module reboots due to the expiration of the timeout period before the operation completes. If you experience host I/O errors or internal RAID controller module reboots, bring the host to a quiescent state and try the operation again.

Syntax

set (allVirtualDisks | virtualDisk ["virtualDiskName"] | virtualDisks ["virtualDiskName1" ... "virtualDiskNameN"] | 
                                 
                                 virtualDisk <wwID>)  (addCapacity = capacityValue(KB|MB|GB|TB|Bytes) | [addPhysicalDisks = (physicalDisk-spec-list)] | 
                                 
                                 cacheFlushModifier=cacheFlushModifierValue | cacheReadPrefetch = (TRUE | FALSE) | cacheWithoutBatteryEnabled=(TRUE | FALSE)
                                 | 
                                 
                                 mediaScanEnabled=(TRUE | FALSE) | replicationCacheEnabled=(TRUE | FALSE) | 
                                 
                                 modificationPriority=(highest | high | medium | low | lowest) |
                                 
                                 owner=(0 | 1) | preReadConsistencyCheck = (TRUE | FALSE) |
                                 
                                 readCacheEnabled=(TRUE | FALSE) | consistencyCheckEnabled = (TRUE | FALSE) | 
                                 
                                 segmentSize = segmentSizeValueuserLabel = userlabelValuewriteCacheEnabled=(TRUE | FALSE) | 
                                 
                                 dataAssuranceDisabled=(TRUE | FALSE) | flashCacheEnabled=(TRUE | FALSE))

Parameters

Parameter	Description
`allVirtualDisks`	The properties for all virtual disks in the storage array.
`virtualDisk` or `virtualDisks`	The name of the specific virtual disk for which you want to define properties. (You can enter more than one virtual disk name if you use the `virtualDisks` parameter.) Enclose the virtual disk name in double quotation marks (" ") inside of square brackets ([ ]).
`virtualDisk`	The World Wide Identifier (WWID) of the virtual disk for which you are setting properties. You can use the WWID instead of the virtual disk name to identify the virtual disk. Enclose the WWID in angle brackets (< >). NOTE: When running this command, do not use colon separators in the WWID.
`addCapacity`	The setting to increase the storage size (capacity) of the virtual disk for which you are defining properties. Size is defined in units of bytes, KB, MB, GB, or TB. The default value is `bytes`. This parameter is not valid for thin virtual disks. NOTE: The maximum capacity is 250 GB.
`addPhysicalDisks`	The setting to add new physical disks to the virtual disk. For dense expansion enclosures, specify the enclosure ID value, the drawer ID value, and the slot ID value for the physical disk. For non-dense expansion enclosures, specify the enclosure ID value and the slot ID value for the physical disk. Enclosure ID values are `0` to `99`. Drawer ID values are `1` to `5`. Slot ID values are `0` to `31`. Enclose the enclosure ID value, drawer ID value, and the slot ID value in parentheses. Use this parameter with the `addCapacity` parameter if you need to specify additional physical disks to accommodate the new size. This parameter is not valid for disk pool virtual disks or for thin virtual disks. Each disk pool must be created from a minimum of 11 physical disks specified. There is no upward limit of physical disks supported in a single disk pool, but the number cannot exceed the number of physical disks supported on the storage array.
`cacheFlushModifier`	The maximum amount of time that data for the virtual disk stays in cache before the data is flushed to physical storage. Valid values are listed in the Notes section.
`cacheReadPrefetch`	The setting to turn on or turn off cache read prefetch. To turn off cache read prefetch, set this parameter to `FALSE`. To turn on cache read prefetch, set this parameter to `TRUE`.
`cacheWithoutBatteryEnabled`	The setting to turn on or turn off caching without batteries. To turn on caching without batteries, set this parameter to `TRUE`. To turn off caching without batteries, set this parameter to `FALSE`.
`mediaScanEnabled`	The setting to turn on or turn off media scan for the virtual disk. To turn on media scan, set this parameter to `TRUE`. To turn off media scan, set this parameter to `FALSE`. (If media scan is disabled at the storage array level, this parameter has no effect.)
`replicationCacheEnabled`	The setting to turn on or turn off the replication cache. To turn on the replication cache, set this parameter to `TRUE`. To turn off the replication cache, set this parameter to `FALSE`.
`modificationPriority`	The priority for virtual disk modifications while the storage array is operational. Valid values are `highest`, `high`, `medium`, `low`, or `lowest`.
`preReadConsistencyCheck`	The setting to turn on or turn off preread consistency checking. Turning on preread consistency checking verifies the consistency of RAID redundancy data for the stripes containing the read data. Preread consistency checking is performed on read operations only. To turn on preread consistency checking, set this parameter to `TRUE`. To turn off preread consistency checking, set this parameter to `FALSE`. NOTE: Do not use this parameter on non redundant virtual disks, such as RAID 0 virtual disks.
`readCacheEnabled`	The setting to turn on or turn off the read cache. To turn on the read cache, set this parameter to `TRUE`. To turn off the read cache, set this parameter to `FALSE`.
`consistencyCheckEnabled`	The setting to turn on or turn off the write cache. To turn on the write cache, set this parameter to `TRUE`. To turn off the write cache, set this parameter to `FALSE`.
`segmentSize`	The amount of data (in KB) that the RAID controller module writes on a single physical disk in a virtual disk before writing data on the next physical disk. Valid values are `8`, `16`, `32`, `64`, `128`, `256`, or `512`
`userLabel`	The new name that you want to give an existing virtual disk. Enclose the new virtual disk name in double quotation marks (" ").
`writeCacheEnabled`	The setting to turn on write cache capability.
`dataAssuranceDisabled`	The setting to turn off data assurance for a specific disk. For this parameter to have meaning, your disk must be capable of data assurance. This parameter changes a virtual disk from one that supports data assurance to a disk that cannot support data assurance. NOTE: This option is only valid for enablement, if the disks support DA. To remove data assurance from a disk that supports data assurance, set this parameter to TRUE. NOTE: If you remove data assurance from a disk, you cannot reset data assurance for that disk. To reset data assurance for the data on a disk, from which you removed data assurance, perform these steps: Remove the data from the disk. Delete the disk. Recreate a new disk with the properties of the deleted disk. Set data assurance for the new disk. Move the data to the new disk.

Notes

When you use this command, you can specify one or more of the optional parameters.

You can apply these parameters to only one virtual disk at a time:

addCapacity
segmentSize
userLabel

Add Capacity, Add Physical Disks, And Segment Size

Setting the addCapacity parameter, the addPhysicalDisks parameter, or the segmentSize parameter starts a long-running operation that you cannot stop. These long-running operations are performed in the background and do not prevent you from running other commands. To show the progress of long-running operations, use the show virtualDisk actionProgress command.

Cache Flush Modifier

Valid values for the cache flush modifier are listed in the following table.

Value	Description
`Immediate`	Data is flushed as soon as it is placed into the cache.
`250`	Data is flushed after 250 ms.
`500`	Data is flushed after 500 ms.
`750`	Data is flushed after 750 ms.
`1`	Data is flushed after 1 s.
`1500`	Data is flushed after 1500 ms.
`2`	Data is flushed after 2 s.
`5`	Data is flushed after 5 s.
`10`	Data is flushed after 10 s.
`20`	Data is flushed after 20 s.
`60`	Data is flushed after 60 s (1 min.).
`120`	Data is flushed after 120 s (2 min.).
`300`	Data is flushed after 300 s (5 min.).
`1200`	Data is flushed after 1200 s (20 min.).
`3600`	Data is flushed after 3600 s (1 hr).
`Infinite`	Data in cache is not subject to any age or time constraints. The data is flushed based on other criteria that are managed by the RAID controller module.

Cache Without Battery Enabled

Write caching without batteries enables write caching to continue if the RAID controller module batteries are completely discharged, not fully charged, or not present. If you set this parameter to TRUE without an uninterruptible power supply (UPS) or other backup power source, you can lose data if the power to the storage array fails. This parameter has no effect if write caching is disabled.

Modification Priority

Modification priority defines the amount of system resources that are used when modifying virtual disk properties. If you select the highest priority level, the virtual disk modification uses the most system resources, which decreases the performance for host data transfers.

Cache Read Prefetch

The cacheReadPrefetch parameter enables the RAID controller module to copy additional data blocks into cache while the RAID controller module reads and copies data blocks that are requested by the host from the physical disk into cache. This action increases the chance that a future request for data can be fulfilled from cache. Cache read prefetch is important for multimedia applications that use sequential data transfers. The configuration settings for the storage array that you use determine the number of additional data blocks that the RAID controller module reads into cache. Valid values for the cacheReadPrefetch parameter are TRUE or FALSE.

Segment Size

The size of a segment determines how many data blocks that the RAID controller module writes on a single physical disk in a virtual disk before writing data on the next physical disk. Each data block stores 512 bytes of data. A data block is the smallest unit of storage. The size of a segment determines how many data blocks that it contains. For example, an 8 KB segment holds 16 data blocks. A 64 KB segment holds 128 data blocks.

When you enter a value for the segment size, the value is checked against the supported values that are provided by the RAID controller module at run time. If the value that you entered is not valid, the RAID controller module returns a list of valid values. Using a single physical disk for a single request leaves other physical disks available to simultaneously service other requests.

If the virtual disk is in an environment where a single user is transferring large units of data (such as multimedia), performance is maximized when a single data transfer request is serviced with a single data stripe. (A data stripe is the segment size that is multiplied by the number of physical disks in the disk group that are used for data transfers.) In this case, multiple physical disks are used for the same request, but each physical disk is accessed only once.

For optimal performance in a multiuser database or file system storage environment, set your segment size to minimize the number of physical disks that are required to satisfy a data transfer request.

Benvenuto

Benvenuto in Dell