On 03/17/13 20:13, Constantine A. Murenin wrote:
If you're dealing with regular platter-based HDDs, would you nonetheless configure the second HDD (which is the target of the `hammer mirror-stream`) as swapcache? Wouldn't it potentially make the performance much worse?
I think for this scenario people tend to be doing: 1) System disk (OS only or OS+packages) on SSD with giant swap partition for swapcache 2) Pair of data drives (primary / secondary) with mirror-stream between primary & secondary You can rate-limit the mirror-stream if you want to reduce the mirroring overhead. In the 2-disk scenario you mention, swapcache on either drive will be reducing performance since the swapcache is in the 'critical path' with respect to mirrored data - although when coupled with bandwidth limiting you might be able to reduce that impact and keep the second platter more 'available' for your swapcache. Obviously, compared to 'real raid' this is a best-effort failover since there can be some delay, but you'll generally get 'just about everything' which is probably fine for many applications. 2c Cheers, - Chris
