Storage Questions Part 1

The project I’m supporting is looking at ‘mid range’ enterprise Fibre Channel storage arrays. As part of the investigation, I perform market surveys of leading vendors. After we narrow down the field, I submit a long list of technical questions. While vendor’s web sites make their array sound like the best thing since sliced bread, the devil is in the details. Often you will uncover technical limitations which may knock the vendor out of the running.

Since my list of questions is pretty lengthy, I’ll break them up into several installments. Of course depending on your requirements, there will likely be additional questions. I broke the questions into various technical areas to help organize them.

1. Controller Details
a. What is the controller architecture? (Active/active concurrent, Active/active non-concurrent, Active/passive, etc.)
b. What is your controller to controller connectivity? (Full cross-bar switch, Full mesh, point to point, other)
c. Min/max controllers?
d. Describe the controller hardware (Standard server with custom software, custom hardware, proprietary ASICs, etc.)?
e. Maximum number of hosts?
f. Cache size and is it mirrored and ECC protected?
g. Minimum/maximum number disks?
h. Maximum storage capacity?
i. Disk capacity, interface speed, spindle speed, and types (FC, SATA, SAS, FATA)?
j. Is there a built-in UPS and what is the run time?
k. If FCAL is used on the back end, are both loops concurrently transferring data or is one loop active and the other standby?

2. LUN Management
a. Minimum/maximum LUN size?
b. Maximum number of LUNs?
c. LUN size increments?
d. If a LUN is presented through four storage ports, how does that count against the overall LUN limit (decrement by one or four)?
e. Dynamic LUN expansion/shrink?
f. Is LUN concatenation required for LUN expansion or large LUNs?
g. Maximum LUNs per storage controller host facing port?

3. Connectivity
a. What are current connectivity options? (4Gb/8Gb FC, 1Gb/10Gb iSCSI, FCoE, NAS, etc.)
b. Minimum and maximum number of host facing ports and type?
c. Can connectivity be easily upgraded to future technology?
d. Any near-term plans for more connectivity options or speeds?
e. Do host ports need to be dedicated to remote replication?

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