[CentOS] Re: question about software Raid 1
John R Pierce
pierce at hogranch.com
Sun Sep 21 19:53:38 UTC 2008
Kay Diederichs wrote:
> BTW, there is - even with current kernels - no speed gain in using
> RAID1 - see http://kernelnewbies.org/KernelProjects/Raid1ReadBalancing .
except, thats wrong. I unwrapped a recent kernel source tarball from
kernel.org and found...
static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
{
struct mirror *m = get_default_mirror(ms);
do {
if (likely(!atomic_read(&m->error_count)))
return m;
if (m-- == ms->mirror)
m += ms->nr_mirrors;
} while (m != get_default_mirror(ms));
return NULL;
}
so it appears its a round robin ...
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