zfs discuss - Jul 2008 - raid or mirror

I''m still confused.
What is a -SAFE- way with two drives if you prepare for hardware
faulure? That is: one drive fails and the system does not go down
because the other drive takes over. Do I need raid or mirror?

-- 
Dick Hoogendijk -- PGP/GnuPG key: 01D2433D
++ http://nagual.nl/ + SunOS sxce snv91 ++

Hi Dick

You want Mirroring.  A Sun system with mirrored disks can be configured to
not go down due to one disk failing.  For this to be valid, you need to also
make sure that the device used for SWAP is mirrored - you won''t believe
how
many times I''ve seen this mistake being made.

To be even MORE safe, you want the two disks to be on separate controllers,
so that you can survive a controller failure too.

note: Technically, mirroring is RAID, to be specific, it is Raid level 1.

  _Johan


On Fri, Jul 11, 2008 at 2:37 PM, dick hoogendijk <dick at nagual.nl>
wrote:
> I''m still confused.
> What is a -SAFE- way with two drives if you prepare for hardware
> faulure? That is: one drive fails and the system does not go down
> because the other drive takes over. Do I need raid or mirror?
>
> --
> Dick Hoogendijk -- PGP/GnuPG key: 01D2433D
> ++ http://nagual.nl/ + SunOS sxce snv91 ++
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>


-- 
Any sufficiently advanced technology is indistinguishable from magic.
Arthur C. Clarke

Afrikaanse Stap Website: http://www.bloukous.co.za

My blog: http://initialprogramload.blogspot.com

ICQ = 193944626, YahooIM = johan_hartzenberg, GoogleTalk jhartzen at gmail.com,
AIM = JohanHartzenberg
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>>>>> "jh" == Johan Hartzenberg <jhartzen at
gmail.com> writes:
    jh> To be even MORE safe, you want the two disks to be on separate
    jh> controllers, so that you can survive a controller failure too.

or a controller-driver-failure.  At least on Linux, when a disk goes
bad, Linux starts resetting controllers and xATA busses and stuff, and
often takes out any nearby drives.  It''s often hard to determine which
drive is actually bad.  Depending on how well-integrated your hardware
is with Solaris and how the drive fails, I suspect this sort of thing
could imagineably happen there, too.
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