On Wed, Oct 8, 2008 at 9:29 PM, Joseph Mocker <[EMAIL PROTECTED]<[EMAIL PROTECTED]> > wrote:
> Hello, > > I haven't seen this discussed before. Any pointers would be appreciated. > > I'm curious, if I have a set of disks in a system, is there any benefit > or disadvantage to breaking the disks into multiple pools instead of a > single pool? > > Does multiple pools cause any additional overhead for ZFS, for example? > Can it cause cache contention/starvation issues? > > Hello Joseph. Firstly, a separate pool for the OS is recommended. The pool from which you boot must be either Mirrored or else a single disk. Booting from Stripes / RaidZ is not supported. Thus if you want to use a stripe or RaidZ you pretty much MUST have a dedicated pool for that. Secondly, if you use whole disks in your pools, it becomes possible to physically "remove" a pool (using zpool export), eg to move a pool to another system. Further, it is recommended to use the same level of redundancy in all vdev's. Eg all vdevs should be mirrored, or the same nr of columns in the stripe or raidz. This is not a restriction, just a strong recommendation. Never ever add multiple slices (partitions) from a single disk device to the same pool - this will cause performance to go down to a crawl! You can not (yet) "break up" a pool, though you can break off a mirror copy. And to stay in line with the above recommendations, you may want more than one pool. For best performance you should use whole-disks in pools, but sometimes for practical reasons you may want to spit a single disk up in slices and add those to separate pools. Hope that helps! _hartz -- Any sufficiently advanced technology is indistinguishable from magic. Arthur C. Clarke Afrikaanse Stap Website: http://www.bloukous.co.za My blog: http://initialprogramload.blogspot.com
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