Administrator Guide

Disk pools and disk pool virtual disks
Disk pooling allows you to distribute data from each virtual disk randomly across a set of physical disks. Disk pooling provides RAID
protection and consistent performance across a set of physical disks logically grouped together in the storage array. Although there is no
limit on the maximum number of physical disks that can comprise a disk pool, each disk pool must have a minimum of 11 physical disks.
Additionally, the disk pool cannot contain more physical disks than the maximum limit for each storage array. The physical disks in each
disk pool must:
• be SAS or nearline SAS
• have the same physical disk speed (RPM)
NOTE: The maximum physical disk speed is 15,000 rpm for standard SAS and 7,200 rpm for 3.5" nearline SAS.
NOTE: In a disk pool, the physical disks must have the same capacities. If the physical disks have different
capacities, the MD Storage Manager uses the smallest capacity among the physical disks in the pool. For example, if
your disk pool is comprised of several 4 GB physical disks and several 8 GB physical disks, only 4 GB on each physical
disk is used.
The data and consistency information in a disk pool is distributed across all of the physical disks in the pool and provides the following
benefits:
• Simplified configuration
• Better utilization of physical disks
• Reduced maintenance
• the ability to use thin provisioning
Topics:
• Difference between disk groups and disk pools
• Disk pool restrictions
• Creating a disk pool manually
• Automatically managing unconfigured capacity in disk pools
• Locating physical disks in a disk pool
• Renaming a disk pool
• Configuring alert notifications for a disk pool
• Adding unassigned physical disks to a disk pool
• Configuring the preservation capacity of a disk pool
• Changing the modification priority of a disk pool
• Changing the RAID controller module ownership of a disk pool
• Checking data consistency
• Deleting disk pool
• Viewing storage array logical components and associated physical components
• Secure disk pools
• Changing capacity on existing thin virtual disks
• Creating thin virtual disk from disk pool
Difference between disk groups and disk pools
Similar to a disk group, you can create one or more virtual disks in a disk pool. However, the disk pool differs from a disk group in the way
data is distributed across the physical disks comprising the pool. Dynamic Disk Pool (DDP) feature dynamically distributes data, spare
capacity, and protects information across a pool of disk drives.
In a disk group, data is distributed across the physical disks based on RAID level. You can specify a RAID level when you create the disk
group, then the data for each virtual disk is written sequentially across the set of physical disks comprising the disk group.
NOTE: Because disk pools can coexist with disk groups, a storage array can contain both disk pools and disk groups.
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