Decide whether to use a pool or a volume group
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You can create volumes using either a pool or a volume group. The best selection depends primarily on the key storage requirements such as the expected I/O workload, the performance requirements, and the data protection requirements.
Reasons to choose a pool or volume group
Choose a pool
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If you need faster drive rebuilds and simplified storage administration, require thin volumes, and/or have a highly random workload.
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If you want to distribute the data for each volume randomly across a set of drives that comprise the pool.
You cannot set or change the RAID level of pools or the volumes in the pools. Pools use RAID level 6.
Choose a volume group
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If you need maximum system bandwidth, the ability to tune storage settings, and a highly sequential workload.
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If you want to distribute the data across the drives based on a RAID level. You can specify the RAID level when you create the volume group.
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If you want to write the data for each volume sequentially across the set of drives that comprise the volume group.
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Because pools can co-exist with volume groups, a storage array can contain both pools and volume groups. |
Feature differences between pools and volume groups
The following table provides a feature comparison between volume groups and pools.
| Use | Pool | Volume group |
|---|---|---|
Workload random |
Better |
Good |
Workload sequential |
Good |
Better |
Drive rebuild time |
Faster |
Slower |
Performance (optimal mode) |
Good: Best for small block, random workload. |
Good: Best for large block, sequential workloads |
Performance (drive rebuild mode) |
Better: Usually better than RAID 6 |
Degraded: Up to 40% drop in performance |
Multiple drive failures |
Greater data protection: Faster, prioritized rebuilds |
Less data protection: Slow rebuilds, greater risk of data loss |
Adding drives |
Faster: Add to pool on the fly |
Slower: Requires Dynamic Capacity Expansion operation |
Thin volumes support |
Yes |
No |
Solid State Disk (SSD) support |
Yes |
Yes |
Simplified administration |
Yes: No hot spares or RAID settings to configure |
No: Must allocate hot spares, configure RAID |
Tunable performance |
No |
Yes |