[linux-lvm] Disk crash on LVM

[Fredrik Skog]

Hi

I'll update you on the progress with my crashed hd.
I'm not yet finished with the pvmove from the device because it won't work 
for very long at a time.
If I have the drive in room temperature and then put it in the freezer for 
25-30mins it works for maybe 15-20min (the drive still in the freezer)and i 
get a pvmove progress of about 15-20%.
If I then shut it down and just let it cool again I get maybe 5-7% more out 
of it before it dies.Prolonging the time in the freezer doesn't seem to help 
at all, in fact sometimes it's worse and the drive doesn't start at all. The 
drive seems to need a few hours warm-up time after it's been frozen and then 
stopped working before I can refreeze it again.
It takes ridiculous amounts of time fiddling with this, but I hope to get to 
the finish soon.
I have not yet tried to increase the readahead.

/Fredrik


----- Original Message ----- 
From: "Peter Keller" <pkeller at globalphasing.com>
To: "LVM general discussion and development" <linux-lvm at redhat.com>
Sent: Monday, September 21, 2009 1:27 PM
Subject: Re: [linux-lvm] Disk crash on LVM


> 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 at gmail.com>
>> To: <linux-lvm at redhat.com>
>> Sent: Saturday, September 19, 2009 4:11 PM
>> Subject: Re: [linux-lvm] Disk crash on LVM
>>
>>
>>> Ray Morris <support at 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
>>>
>>>
>>>
>>> _______________________________________________
>>> linux-lvm mailing list
>>> linux-lvm at redhat.com
>>> https://www.redhat.com/mailman/listinfo/linux-lvm
>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>> _______________________________________________
>> linux-lvm mailing list
>> linux-lvm at redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-lvm
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>
> -- 
> 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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