On Tue, 28 Apr 2009, Richard Elling wrote:
I suppose if you could freeze the media to 0K, then it would not decay.
But that isn't the world I live in :-). There is a whole Journal devoted
to things magnetic, with lots of studies of interesting compounds. But
from a practical perspective, it
On Mon, Apr 27, 2009 at 8:25 PM, Richard Elling richard.ell...@gmail.comwrote:
I do not believe you can achieve five 9s with current consumer disk
drives for an extended period, say 1 year.
Just to pipe up, while very few vendors can pull it off, we've seen five 9's
with Hitachi gear using
On Tue, Apr 28, 2009 at 10:08 AM, Tim t...@tcsac.net wrote:
On Mon, Apr 27, 2009 at 8:25 PM, Richard Elling richard.ell...@gmail.com
wrote:
I do not believe you can achieve five 9s with current consumer disk
drives for an extended period, say 1 year.
Just to pipe up, while very few
On Tue, Apr 28, 2009 at 9:42 AM, Scott Lawson
scott.law...@manukau.ac.nz wrote:
Mainstream Solaris 10 gets a port of ZFS from OpenSolaris, so its
features are fewer and later. As time ticks away, fewer features
will be back-ported to Solaris 10. Meanwhile, you can get a production
support
On Mon, 27 Apr 2009 18:25:42 -0700, Richard Elling
richard.ell...@gmail.com wrote:
The concern with large drives is unrecoverable reads during resilvering.
One contributor to this is superparamagnetic decay, where the bits are
lost over time as the medium tries to revert to a more steady state.
kn == Kees Nuyt k.n...@zonnet.nl writes:
kn Some high availablility storage systems overcome this decay by
kn not just reading, but also writing all blocks during a
kn scrub.
sounds like a good idea but harder in the ZFS model where the software
isn't the proprietary work of the
Tim wrote:
On Mon, Apr 27, 2009 at 8:25 PM, Richard Elling
richard.ell...@gmail.com mailto:richard.ell...@gmail.com wrote:
I do not believe you can achieve five 9s with current consumer disk
drives for an extended period, say 1 year.
Just to pipe up, while very few vendors can
Kees Nuyt wrote:
On Mon, 27 Apr 2009 18:25:42 -0700, Richard Elling
richard.ell...@gmail.com wrote:
The concern with large drives is unrecoverable reads during resilvering.
One contributor to this is superparamagnetic decay, where the bits are
lost over time as the medium tries to revert to
On Apr 28, 2009, at 18:02, Richard Elling wrote:
Kees Nuyt wrote:
Some high availablility storage systems overcome this decay
by not just reading, but also writing all blocks during a
scrub. In those systems, scrubbing is done semi-continously
in the background, not on user/admin demand.
On Tue, Apr 28, 2009 at 4:52 PM, Richard Elling richard.ell...@gmail.comwrote:
Well done! Of course Hitachi doesn't use consumer-grade disks in
their arrays...
I'll also confess that I did set a bit of a math trap here :-) The trap is
that if you ever have to recover data from
On Tue, 28 Apr 2009, Miles Nordin wrote:
* it'd be harmful to do this on SSD's. it might also be a really
good idea to do it on SSD's. who knows yet.
SSDs can be based on many types of technologies, and not just those
that wear out.
* it may be wasteful to do read/rewrite on an
On Tue, 28 Apr 2009, Richard Elling wrote:
Yes and there is a very important point here.
There are 2 different sorts of scrubbing: read and rewrite.
ZFS (today) does read scrubbing, which does not reset the decay
process. Some RAID arrays also do rewrite scrubs which does reset
the decay
On Tue, 28 Apr 2009, Tim wrote:
I'll stick with the 3 year life cycle of the system followed by a
hot migration to new storage, thank you very much.
Once again there is a fixation on the idea that computers gradually
degrade over time and that simply replacing the hardware before the
On Tue, Apr 28, 2009 at 11:12 PM, Bob Friesenhahn
bfrie...@simple.dallas.tx.us wrote:
On Tue, 28 Apr 2009, Tim wrote:
I'll stick with the 3 year life cycle of the system followed by a hot
migration to new storage, thank you very much.
Once again there is a fixation on the idea that
Bob Friesenhahn wrote:
On Tue, 28 Apr 2009, Richard Elling wrote:
Yes and there is a very important point here.
There are 2 different sorts of scrubbing: read and rewrite.
ZFS (today) does read scrubbing, which does not reset the decay
process. Some RAID arrays also do rewrite scrubs which
Leon,
RAIDZ2 is ~equivalent to RAID6. ~2 disks of parity data. Allowing a
double drive
failure and still having the pool available.
If possible though you would be best to let the 3ware controller expose
the 16 disks as a JBOD to ZFS and create a RAIDZ2 within Solaris as you
will then
gain
On Mon, Apr 27, 2009 at 4:51 PM, Scott Lawson
scott.law...@manukau.ac.nz wrote:
If possible though you would be best to let the 3ware controller expose
the 16 disks as a JBOD to ZFS and create a RAIDZ2 within Solaris as you
will then
gain the full benefits of ZFS. Block self healing etc etc.
Michael Shadle wrote:
On Mon, Apr 27, 2009 at 5:32 PM, Scott Lawson
scott.law...@manukau.ac.nz wrote:
One thing you haven't mentioned is the drive type and size that you are
planning to use as this
greatly influences what people here would recommend. RAIDZ2 is built for
big, slow SATA
On Mon, 27 Apr 2009, Michael Shadle wrote:
I was still operating under the impression that vdevs larger than 7-8
disks typically make baby Jesus nervous.
Baby Jesus might not be particularly nervous but if your drives don't
perform consistently, then there will be more chance of performance
Richard Elling wrote:
Some history below...
Scott Lawson wrote:
Michael Shadle wrote:
On Mon, Apr 27, 2009 at 4:51 PM, Scott Lawson
scott.law...@manukau.ac.nz wrote:
If possible though you would be best to let the 3ware controller
expose
the 16 disks as a JBOD to ZFS and create a
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