Hello Pawel,

Thursday, April 5, 2007, 3:10:11 PM, you wrote:

PJD> Hi.

PJD> What do you think about adding functionality similar to disk's spare
PJD> sectors - if a sector die, a new one is assigned from the spare sectors
PJD> pool. This will be very helpful especially for laptops, where you have
PJD> only one disk. I simulated returning EIO for one sector from a one-disk
PJD> pool and as you know system paniced:

PJD> panic: ZFS: I/O failure (write on <unknown> off 0: zio
PJD> 0xc436d400 [L0 zvol object] 2000L/2000P DVA[0]=<0:4000:2000>
PJD> fletcher2 uncompressed LE contiguous birth=11 fill=1
PJD> 
cksum=90519dcb617667ac:e96316f8a73d7efc:8ca812fc04509f9b:9b9632c6959cbd71): 
error 5

PJD> From what I saw, ZFS retried to write to this sector once again before
PJD> panicing, but why not just try another block? And maybe remember the
PJD> problematic block somewhere. Of course this won't safe us when read
PJD> operation fails, but should work quite well for writes.

PJD> Not sure how vdev_mirror works exactly, ie. if it needs both mirror
PJD> components to be identical or if the only guaranty is that they have the
PJD> same data, but not exactly in the same place. If the latter, proposed
PJD> mechanism could be also used as a part of the self-healing process, I
PJD> think.


IIRC it was discussed here some time ago (check archives) and it was
stated that ZFS does not require in mirror case block to be in the
same position on all mirrors. Also in read scenario if you couldn't
read you try to self-heal (it's now) and if you still can't write you
write to new location.

Now I don't know how it's with raid-z*


-- 
Best regards,
 Robert                            mailto:[EMAIL PROTECTED]
                                       http://milek.blogspot.com

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