RAID 5 (6+1) Pool on VNX 5300

Hello,

Please find the CLI guide on this link

https://mydocs.emc.com/VNX/relatedDocs.jsp?rd=RelatedDocs_1

EMC VNX Command Line Interface Reference for Block

You could add un-recommended (check best practices guide below) number of drives into a pool by over-riding the warning, however performance would be impacted

https://support.emc.com/docu42660_Applied_Best_Practices_Guide:_EMC_VNX_Unified_Best_Practices_for_Performance.pdf?language=en_US

Regards,

Sudheer

Reading the CLI guide in a bit more detail and I think you can use the -rdrivecount 7 parameter but you don't have to. You have to create the pool with 7 drives only in order to get 6+1. When you create the pool and select only 7 drives the VNX will automatically create 6+1; no need to specify -rdrivecount. The -rdrivecount parameter comes into play in the following example. Let's say you want to create a pool (using CLI) that is using 8+1. If you don't use the -rdrivecount parameter the VNX will create two private RAID Groups; 4+1 and 3+1. That's where the -rdrivecount comes into play. If you create the same pool with the rdrivecount 9 the VNX will create one private RAID Group with 8+1

Hi! Today i read this guide and try to create storage pool with next

command parameters:

"naviseccli -user admin -password P@ssw0rd -address 10.56.232.137

-scope 0 storagepool -create -disks 0_0_4 0_0_5 0_0_6 0_0_7 0_0_8

0_0_9 0_0_10 0_0_11 0_0_12 0_0_13 0_0_14 1_0_0 1_0_1 1_0_2 1_0_3 1_0_4

1_0_5 1_0_6 1_0_7 1_0_81_0_9 1_0_10 1_0_11 1_0_12 1_0_13 0_1_0 0_1_1

0_1_2 0_1_3 0_1_4 0_1_5 0_1_6 -rtype r_5 -rdrivecount 7 -skiprules"

But i receive next message:

The creation of storagepool did not succeed. The storagepool will not

be created.

Rule Messages:

Unsupported RAID drive count. The following values are supported for

RAID 5: 5, 9

So, unfortunately, i think that it's not possible create RAID 5 with

6+1 type parity disks...

On Mon, 26 Aug 2013 12:08:35 -0700

Try running that command but only specify 7 drives, see if that works. You can expand the pool later by adding 7 more drives but curious if it works by specifying 7 drives only.

Thank for the help, Ernes!

On Tue, 27 Aug 2013 07:18:37 -0700

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glen

Hi! Thanks all for answers. Correct answer that supported rdrivecount is 5(4+1) or 9(8+1). No other count of drives available for selection. We added 28 SAS disks to Pool with rdrive count 8+1 and summary size of Pool is 15014.268 Gb.This is what we need. Thank you guys, you are really helped.

You could have also btw, selected -rdrivecount 5 and add 7 drives at a time and get the desired: R5 (6+1) pRG.  Again, by deriving it through the logic as referenced here:

https://community.emc.com/message/696115#696115

Either way works, but the key for both would be to create then expand in increments of 7 drives at a time and not all 28 drives at once.

Correct, those are the only choices as noted above.  When you added the 28 drives, as suggested above again in order to get your desired: R5 (6+1) pRG's.  Did you also create and then expand the tier in increments of 7 drives at a time (while also selecting -rdrivecount 9)?

If not and you added all at once, then if you run the commands above, you would actually have created the following underlying pRG's by also following the logic as noted in a separate post that was referenced above:

2x R5 (8+1)

1x R5 (9+1)

(If I wanted I could also answer on my own if I fired up the capacity calculator and compare to the final usable capacity you noted below... meh... easier to ask}