[CentOS] Re: question about software Raid 1

Sun Sep 21 23:59:50 UTC 2008
John R Pierce <pierce at hogranch.com>

> This makes sense.  I'm pretty sure that tests that I've run in the past
> using bonnie++ or iozone showed faster reads with raid1 than with a
> single drive.  I would think that if the drives are on seperate
> controllers (and depending upon the performance/capacity of the drives
> and controllers), there could be notable improvements.

with SATA or SAS, of course, every drive is on its own channel.   even 
with PATA, at 100 or 133Mbyte/sec, only the fastest newer drives would 
saturate the bus doing two transfers concurrently.

now, after i wrote what I did above, I dug up the kernel.org 2.6.18 
kernel that RHEL/CentOS 5 is based on, and it still had the older code 
sequence as shown in that 'to do' list entry...    but I didn't run the 
RHEL patch sequences against it, its quite possible RHEL retrofitted 
this patch to it.