how do the raid groups cooperate?

[coopci777]

If there are more than one raid groups in an unmirrored aggregate or in a plex of a mirrored aggregate, are these raid groups concatnated or they are treated as a big raid0?

Since there can be various sized raid groups , I guessed they are concatnated, but did not find any proof or doc about this.

[radek_kubka]

Hi and welcome to the Communities!

I am not 100% sure what do you mean by 'concatenated' vs. RAID0, as this actually may be the same.

In a practical terms though, when you have multiple RAID groups in the same aggregate, a newly created volume will be stripped across all RAID groups, not just one.

Regards,

Radek

[coopci777]

They are definetely not the same thing:

raid0:   http://en.wikipedia.org/wiki/Raid_0#RAID_0 and

concatencate:   http://en.wikipedia.org/wiki/JBOD#Concatenation_.28SPAN.2C_BIG.29

what if the aggr is expanded with new raid groups? Are the old vols restripped?

[radek_kubka]

OK, fair enough - so RAID groups are not concatenated, as you do not need to fill up the first to use the next one.

Re old volumes - they are not automatically restripped when you add new disks, so reallocating them usually makes sense (see this interesting story from Chris: http://communities.netapp.com/groups/chris-kranz-hardware-pro/blog/2010/03/11/hot-spindles)

Regards,
Radek