Storage Questions Part 2

1. Snaphots
a. What is the maximum number of read-only and read-write snapshots per LUN?
b. Is a separate pool (reserve) of disk space required for snapshot use?
c. Are snapshots space efficient?
d. If a LUN has 10 read/write snapshots, and if the source LUN is modified, are 10 copies of that data made or do all snapshots reference the single new block?
e. Does the array support consistency groups? Maximum limits of the groups?
f. Must the snapshot of a volume use the same RAID level?
g. Can snapshots be scheduled, and at what intervals?
h. Can snapshots be set to automatically expire?

2. Thin provisioning
a. Does the array support thin provisioning?
b. Will the array reclaim previously allocated but now unused space? For example, a 1TB LUN had 700GB of physical data which was reduced to 100GB. What happens to that 600GB of allocated storage?

3. Performance/QoS
a. Does the array differentiate between various performance ‘zones’ of a disk, such as outer tracks and inner tracks?
b. What performance tiers can be created? (RAID1, 15K FC disks, outer tracks vs. RAID5, SATA, inner tracks, etc.)
c. Can LUNs be migrated non-disruptively between tiers?
d. Is there any automated data progression between performance and protection tiers?
e. If so, is this at the LUN level or more granular such as block level? For example, could a single LUN have some blocks on high performance disks while other less used blocks are on nearline disks?
f. Can LUNs be assigned performance parameters based on workload (Exchange, SQL, VMware, etc.)?
g. Are there any published SPC-1 benchmarks?

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