Richard Elling wrote:
There are many error correcting codes available. RAID2 used Hamming
codes, but that's just one of many options out there. Par2 uses
configurable strength Reed-Solomon to get multi bit error
correction. The par2 source is available, although from a ZFS
perspective is hi
Christian Auby wrote:
On Wed, 8 Jul 2009, Moore, Joe wrote:
That's true for the worst case, but zfs mitigates
that somewhat by
batching i/o into a transaction group. This means
that i/o is done every
30 seconds (or 5 seconds, depending on the version
you're running),
allowing multiple writes
> On Wed, 8 Jul 2009, Moore, Joe wrote:
> That's true for the worst case, but zfs mitigates
> that somewhat by
> batching i/o into a transaction group. This means
> that i/o is done every
> 30 seconds (or 5 seconds, depending on the version
> you're running),
> allowing multiple writes to be wr
Haudy Kazemi wrote:
Adding additional data protection options are commendable. On the
other hand I feel there are important gaps in the existing feature
set that are worthy of a higher priority, not the least of which is
the automatic recovery of uberblock / transaction group problems
(see
Adding additional data protection options are commendable. On the
other hand I feel there are important gaps in the existing feature
set that are worthy of a higher priority, not the least of which is
the automatic recovery of uberblock / transaction group problems (see
Victor Latushkin's
Haudy Kazemi wrote:
Daniel Carosone wrote:
Sorry, don't have a thread reference
to hand just now.
http://www.opensolaris.org/jive/thread.jspa?threadID=100296
Note that there's little empirical evidence that this is directly applicable to
the kinds of errors (single bit, or otherwise) th
Daniel Carosone wrote:
Sorry, don't have a thread reference
to hand just now.
http://www.opensolaris.org/jive/thread.jspa?threadID=100296
Note that there's little empirical evidence that this is directly applicable to
the kinds of errors (single bit, or otherwise) that a single failing d
On Wed, 8 Jul 2009, Moore, Joe wrote:
The copies code is nice because it tries to put each copy "far away"
from the others. This does have a significant performance impact when
on a single spindle, however, because each logical write will be written
"here" and then a disk seek to write it to
Christian Auby wrote:
> It's not quite like copies as it's not actually a copy of the data I'm
> talking about. 10% parity or even 5% could easily fix most disk errors
> that won't result in a total disk loss.
(snip)
> I don't see a performance issue if it's not enabled by default though.
The co
> Sorry, don't have a thread reference
> to hand just now.
http://www.opensolaris.org/jive/thread.jspa?threadID=100296
Note that there's little empirical evidence that this is directly applicable to
the kinds of errors (single bit, or otherwise) that a single failing disk
medium would produce.
> Do you have data to back this up?
It's more of a logical observation. The random data corruption I've had up
through the years have generally either involved a single sector or two or a
full disk failure. 5% parity on a 128KB block size would allow you to lose
6.4KB, or ~10 512 byte sectors.
Christian Auby wrote:
You are describing the copies parameter. It really
helps to describe
it in pictures, rather than words. So I did that.
http://blogs.sun.com/relling/entry/zfs_copies_and_data
_protection
-- richard
It's not quite like copies as it's not actually a copy of the data I
> You are describing the copies parameter. It really
> helps to describe
> it in pictures, rather than words. So I did that.
> http://blogs.sun.com/relling/entry/zfs_copies_and_data
> _protection
> -- richard
It's not quite like copies as it's not actually a copy of the data I'm talking
about.
There was a discussion in zfs-code around error-correcting (rather than just
-detecting) properties of the checksums currently kept, an of potential
additional checksum methods with stronger properties.
It came out of another discussion about fletcher2 being both weaker than
desired, and flawed
On Tue, 2009-07-07 at 17:42 -0700, Richard Elling wrote:
> Christian Auby wrote:
> > ZFS is able to detect corruption thanks to checksumming, but for single
> > drives (regular folk-pcs) it doesn't help much unless it can correct them.
> > I've been searching and can't find anything on the topic,
Christian Auby wrote:
ZFS is able to detect corruption thanks to checksumming, but for single drives
(regular folk-pcs) it doesn't help much unless it can correct them. I've been
searching and can't find anything on the topic, so here goes:
1. Can ZFS do parity data on a single drive? e.g. x%
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