Coming a bit late to this thread...
On Sat, 19 Sep 2009, Fredrik Skog wrote:
Thanks guys for your input on the matter.
I lenghtened the power cables and bought a full lenght SATA cable. Now the
disk is in the freezer and in progress with pvmove. 10% now. so far so good.
The reason i decided for the pvmove instead of dd or dd_rescue was the fact
that i tried a pvmove before, so the process was already started but it
stopped working on 1%. Now with a frozen and working disk it continued from
where it left off.
I have found that with sequential reads like this, adjusting the readahead
of the device with something like 'blockdev --setra nnn' can dramatically
shorten the time needed to read the whole device.
The default usually seems to be too low when reading sequentially. If you
haven't already adjusted it, try adjusting it upwards. Values like 8192 or
16384 may help.
Good luck,
Peter.
I can tell you how it turned out later.
Thanks
/Fredrik
----- Original Message ----- From: "André Gillibert" <rcvxdg@gmail.com>
To: <linux-lvm@redhat.com>
Sent: Saturday, September 19, 2009 4:11 PM
Subject: Re: Disk crash on LVM
Ray Morris <support@bettercgi.com> wrote:
[...]
Then dd from the old copy of the LV to the new:
dd if=/dev/org/$1 bs=64M iflag=direct |
dd of=/dev/copy/$1 bs=64M oflag=direct
That piped dd is 2-3 times faster than the "obvious"
way to run dd.
[...]
The issue with dd is that if any read() fails, it skips the entry (64M) and
doesn't write to the output, making the output file smaller than the input
file.
with conv=sync,noerror, it's better, but, still loosing a whole 64M block
at once is a bad thing.
That's why I think dd_rescue would be better.
<http://www.garloff.de/kurt/linux/ddrescue/>
If it still gets warm too fast, I've heard that storing the hard drive in a
freezer 24 hours may make it work again.
<http://geeksaresexy.blogspot.com/2006/01/freeze-your-hard-drive-to-recover-data.html>
If it crashes when dd or dd_rescue fails, it's possible to continue copying
later, from the point it failed.
--
André Gillibert
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--
Peter Keller Tel.: +44 (0)1223 353033
Global Phasing Ltd., Fax.: +44 (0)1223 366889
Sheraton House,
Castle Park,
Cambridge CB3 0AX
United Kingdom
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