[OpenIndiana-discuss] Raid type selection for large # of ssds

Roel_D openindiana at out-side.nl
Fri Oct 5 17:38:40 UTC 2012


Imho you need to differentiate between "nice to keep" and "need to keep".

I see absolutely no use for 24 drives in a raid config. Because what do you think you will gain outside the great "I have 24 drive raidz config!" quotes at the bar?

You have userdata and you have OS data. OS data is not very expensive, backing up a virtual OS each night will keep you up and running for ages. And even the costs of reinstalling an OS are low. 

Userdata can be expensive if it gets lost, but even then...building a raid 10 for someone's homedirectory filled with pictures of his family could be a little to much.

You should inventory which data may not be lost and where it resides. These data/directories can (maybe) be stored on, for example, an iscsi target (running inside a zone) with 2 to 4 drives in raidz. 

You can the backup the whole zone during off-hours. This will keep real data protected against lost. 

At our office we ran out of backupspace. Our ICT supplier adviced a 1 terrabyte backup solution. 
I decided to investigate this and we discovered that we backupped 500GB of pdf files that were old and new version were downloadable on the internet within seconds. And....the last 2 years our orderingsystem was left out the backup because of the lack of space. We had the backup because we couldn't affort to loose the orderingsystem..

Kind regards, 

The out-side

Op 5 okt. 2012 om 18:39 heeft Grant Albitz <GAlbitz at Albitz.Biz> het volgende geschreven:

> I feel bad asking this question because I generally know what raid type to pick.
> I am about to configure 24 256gig ssd drives in a ZFS/Comstar deployment. This will serve as the datastore for a vmware deployment. Does anyone know what raid level would be best. I know the workload will determine alot, but obviously there is varying workload across a vmware environment. Since we are talking about ssds I dont see a particular reason to not create 1 big zfs pool, with the exception that I know people generally try to keep the drive count from getting out of control. Raid 10 seems like a waste of space with little benefit in performance in this case. i am leaning towards raid z2 but wanted to get everyones input.
> The datastore will host a fileserver, and exchange server for about 50 users. The environment is all 10g and they have solid states in all desktops so essentially that is the reason for such a large SSD deployment for a small # of users.
> There seems to be varying opinions, especially when you factor in trying to keep writes low for ssds.
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