HP StorageWorks Enterprise Virtual Array Cluster FIO Starter Kit Guide de l'utilisateur télécharger pdf (Page 123)

Storage pool size considerations

When comparing small pools to large pools, the large pools have an advantage. Because there are

fewer, they are easier to manage, and since the pool free space in the same pool is used for snapshots,

asynchronous mirroring, and thin provisioning, there is a less likelihood of stranded capacity. Small

pools, however, may allow the administrator to better partition the storage for various user groups,

or to have a pool per back-end array to ease troubleshooting.

Using thinly provisioned virtual disks

In general, a thin volume has similar performance characteristics to those of a regular volume; however,

when additional capacity is required by a thin volume, additional time is needed to complete the

write. This may be observed after the creation of a thinly provisioned virtual disk when random writes

may trigger many expansions, and is less likely to occur after a volume has been used for a while.

To avoid this first write penalty, pre-write a significant portion of the volume and then delete the data.

The EVA Cluster allows for an initial allocation of up to (the smaller of) 10% of the size of the virtual

disk or 32 GB. Growth of the allocation is based on the size of the initial allocation.

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HP StorageWorks Enterprise Virtual Array Cluster FIO Starter Kit Guide de l'utilisateur Page 123