Setting Raid Rebuild Rate; General Guidelines For Setting The Raid Rebuild Rate; Setting The Raid Rebuild Rate; Reconfiguring Raid - HP StorageWorks P4000 User Manual

For instance, your SAN uses four 12 TB HP LeftHand P4500s configured with RAID 10. You purchase
two additional 12 TB HP LeftHand P4500s which you want to configure with RAID 5.
In the existing cluster, a single 12 TB HP LeftHand P4500 configured with RAID 10 provides 6 TB of
usable storage. A single 12 TB HP LeftHand P4500 configured with RAID 5 provides 9 TB of usable
storage. However, due to the restrictions of how the cluster uses capacity, the 12 TB HP LeftHand
P4500 configured with RAID 5 will be limited to 6 TB per storage system.
In general, the best practice is to avoid mixing configurations of various numbers or capacities of
drives, so that the SAN fully utilizes the available capacity of each cluster.

Setting RAID rebuild rate

Choose the rate at which the RAID configuration rebuilds if a disk is replaced.
NOTE:
The RAID rebuild rate cannot be set on a VSA, since there is no physical hardware to rebuild.

General guidelines for setting the RAID rebuild rate

Use the following guidelines when deciding where to set the RAID rebuild rate.
• Setting the rate high is preferred for rebuilding RAID quickly and protecting data. However, it
slows down user access to data.
• Setting the rate low allows users quicker access to data during the rebuild, but slows the rebuild
rate.
CAUTION:
In the IBM x3650, the RAID rebuild rate cannot be changed from high. This setting may affect the
SAN if a disk configured with RAID 10 or RAID 5 needs to be rebuilt.

Setting the RAID rebuild rate

1. In the navigation window, log in to a storage system and select the Storage category.
2. On the RAID Setup tab, click RAID Setup Tasks and select the RAID Rebuild Rate Priority choice.
The RAID Rebuild Rate Priority window opens. This window will be different for different storage
systems, as described above.
3. Change the rebuild settings as desired.
4. Click OK.
The settings are then ready when a RAID rebuild takes place.

Reconfiguring RAID

Reconfiguring RAID on a storage system or a VSA destroys any data stored on that storage system.
For VSAs, there is no alternate RAID choice, so the only outcome for reconfiguring RAID is to wipe
out all data.
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