Posted by: Anonymous
on January 21, 2008 02:22 PM
I'm going to put out a guess here about Linux RAID1, but would be happy if anyone has a more informed opinion...
I'm going to guess/hope that RAID1 is capable of being quite flexible, based on the current workload. First off, it should never be necessary to read both drives for any given read request, unless one drive returns an error. In normal lightly-loaded operation, I would expect/hope for RAID1 to ping-pong requests between the 2 drives, both in order to equalize the drive usage and to get "striping-like" benefits of RAID0 out of RAID1. Under more heavily-loaded conditions I would expect/hope for RAID1 to seek-optimize the requests, essentially sending one stream of requests to one drive, and another stream of requests to the other drive. In this way, RAID1 could do some heavy seek optimization under multitasking that RAID0 can't.
I run kernel RAID1 simply for the data integrity, and had kind of hoped for the type of actions that appear to be shown in these benchmarks.