Hard Disk IDs in Linux

Dan Egli ddavidegli at gmail.com
Thu Mar 14 01:22:04 MDT 2013


*Perhaps I am misunderstanding how the RAID functionality works. I know it
has to take a while to rewrite the contents of a 4TB drive. Even maxing the
write speed of most hard disk drives that's going to take a few hours I
bet. However, for the overall write speeds of the array during normal
operations I'd imagine it would be somewhat fast because it's splitting the
write operations between 30 disks (for raid6) at once. RAID10 works as well
I know. But considering the amount of mirroring going on that would
duplicate the writing, that would seem to slow it down. *

* *

*Anyway, with any luck it will become a moot point in the next few days.
I'm hoping to convince my boss that such a large machine is not needed.
We'll see.*

* *

*Thanks!*

* *

*--- Dan*


On Tue, Mar 12, 2013 at 11:17 PM, Barry Roberts <blr at robertsr.us> wrote:

> On Tue, Mar 12, 2013 at 11:35 AM, Corey Edwards <tensai at zmonkey.org>
> wrote:
> >
> > On 03/12/2013 10:05 AM, Michael Torrie wrote:
> > > Personally, if I had that many disks, I would do RAID10.  Basically
> > > that's striping across pairs of RAID1 disks.  Or use sets of 4 disks in
> > > a RAID-6 setup, and stripe across them.  Same efficiency as RAID10, but
> > > you can lose up to 2 out of any 4 disks.  Either way, 50% efficiency,
> > > but I'd sleep way better at night.
> >
> > I have to agree on RAID10. Disk is cheap; downtime is expensive.
>
> RAID6 is slow.  Rebuilding the array after you lose a 4TB drive is
> going to take FOREVER.  After you test that and time it and compare
> normal write speeds RAID6-RAID10, if you still want RAID6, have fun.
> I suspect you won't.
>
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