Advice on Disk Configuration for SCV2020

Question

Hi there, I had a couple queries I was hoping to get some help with.  We're implementing a new SAN and Server setup and as part of this are procuring an SCV2020 with 24 x 1.2TB 15K drives. I've been reading through the various articles to plan our implementation but I can't really find anything with regards to the best practice around provisioning this storage pool.  We will be adding a 3 node failover cluster with Windows to access this SAN, there isn't any need to give machines a higher priority than others so I'm just wondering if I should create one Cluster Shared Volume across the entire storage array.   Would you recommend this or do you think I should go down the route of having numerous CSVs, indeed, is there even any benefit to this? Finally; in reading through the Storage Management user manual I saw something saying 2000 series cannot access more than 20 disks at a time (and anything over that would be spare).  As we've been spec'd with 24 disks am I to assume 4 would be hot spares (overkill) or does the 2020 allow me to access more of them (ideally I just want 1 hot spare). Any advice would be greatly appreciated.

KillerBotK · Accepted Answer

Ah, didn't pick up on the fact it was per 20, I assumed it was anything above 20.

I think based no that I'll create 2 CSVs, with 12 drives each (1 of each being spare). That'll do nicely.

Thank you so much Sam.

DELL-Sam L · Answer

Hello KillerBotK,

Here is the link to the Administrator guide for your SCV2020 & if you look on page 58 it explains how many drives you are required to have as spare drives in your SCV2020. http://topics-cdn.dell.com/pdf/dell-compellent-sc4020_Administrator%20Guide_en-us.pdf

It is best to have multiple CSV. You can have one single CSV, if you do though that CSV will be owned by a single controller. If you have multiple CSV, then they will be split between both controllers owning them.

Please let us know if you have any other questions.

KillerBotK · Answer

Thank you for that Sam.

That guide looks like where I saw the initial flag around drive pools. I've copied out the relevant lines here;

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For SCv2000 and SC7020,Storage Center groups drives into groups of no more than 21 drives. Storage Center designates one drive in each group of drives as a spare drive. For example, a disk class containing 21 drives will have 20 managed drives and one spare drive. A disk class with 22 drives will have 20 managed drives and two spare drives.

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Assuming that this also applies to the SCv2020 I'm guessing what we've been spec'd is going to end up with 4 spare drives right?

Thank you for your notes on the CSVs too. I hadn't considered that. We have a dual controller model so would you advise 2 CSVs or would you go even further and say 3/4?

DELL-Sam L · Answer

Hello KillerBotK,

For your current setup you will need 2 spare drives. For every 20 drives there has to be 1 spare drive. Since you have 24 drives you will have a minimum of 2 spare drives.

As for the CSV that is up to you. I would say in my own opinion that a minimum of 2.

Please let us know if you have any other questions.

Compellent

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