2009-02-09 03:14 PM
Am trying to add new 300 Gig unassigned disks to an exisiting aggr that has a RAID group that has not yet reached its limit of disks.
But I do not want to add it to an exisiting RAID. I want to create a new one.
The reason i do not want to assign it to the existing RAID group is because the exisiting RAID group has drives that are 144 Gigs in size. I dont want to mix and match drive sizes in the same RAID group and have the software rightsize it and thus waste storage space.
I do not know what the commands are to create a new RAID when an exisiting RAID is not yet full.
Hopefully i am making sense here....
Thanks for any and all help
2009-02-09 04:17 PM
You can either reduce the raidsize of the aggregate to the current number of disks which will force it into a new raid group (aggr options aggr_name raidsize num)
Or you should be able to force adding new disks into a new raid group. I've never tried this myself, but it's in clear on my filer sim!
aggr add aggr_name -g new num_disks
When prompted, you can [p]review the new raid layout just to make sure...
2009-02-09 04:53 PM
Thanks for the info but what is the command to create a new RAID group?
And what happens after we reduce the raidsize of the aggreagte? Does that stay or can we go back in and then make it the original size? and If we do make it back to the original size, what happens to the original RAID group?
Confused you enough?
thanks for the help though.
2009-02-09 05:00 PM
You don't tell it to create a new RAID group directly, you tell it to add disks into the aggregate. With "-g new" in the aggr add command you are telling it to add all the new disks into a new RAID group and not to expand any existing ones, which I believe is what you are trying to achieve?
If you shrink the raidsize, then yes, add the new disks and then grow it afterwards back to the default (16). But I think forcing the "-g new" switch on aggr add will give you what you are trying to do. All new disks you add into the aggregate will get added as a new RAID group.
Fundamentally however, you'll end up with uneven data across the disks when you start to fill up your storage. Is there any reason you dont want to create a new aggregate just for these new disks? Are you adding these disks for performance or for a new storage pool?
2009-02-09 05:04 PM
Okay, makes total sense then
yup, I think what you want is "aggr add aggr_name -g new num_disks" and this will add your new 300's into the existing aggregate, but force them into a new RAID group regardless of anything that already exists.
Hope it helps!
2009-02-10 09:36 AM
Found this article...
Essentially saying we can mix and match different size drives and it will not be rightsized after the parity is taken into account.
2009-02-10 09:41 AM
That article is a little old and uses traditional volumes as it's examples.
I think I'd personally prefer to have the different disk sizes within a new RAID group, even if it works otherwise, I would feel more confident doing it that way. The RAID stripes would then be aligned to the same disk types. Although this may not make any technical difference, it's just the way I would do things.