Re: [Xen-users] Lost images..

["Stephan Viljoen" <steph@xxxxxxxxx>]

Ok , I think I understand now. 

2354 ?        Sl     3:36 /usr/lib/xen/bin/qemu-dm -d 4 -serial pty 
-domain-name test-01 -videoram 4 -k en-us -vnc 0.0.0.0:0 -vncunused -M xenpv
So if the domains runs under PID 2354 for instance , then I should be able to 
recover the image from the following folder ?
/proc/2354/fd 

Here's the content of the directory , how do I actually go about recovering the 
actual disk image ?

dr-x------ 2 root root  0 Jun 26 15:46 .
dr-xr-xr-x 8 root root  0 Jun 26 15:45 ..
lr-x------ 1 root root 64 Jun 26 15:46 0 -> /dev/null
l-wx------ 1 root root 64 Jun 26 15:46 1 -> /var/log/xen/qemu-dm-test-01.log
lrwx------ 1 root root 64 Jun 26 15:46 10 -> /proc/xen/xenbus
lr-x------ 1 root root 64 Jun 26 15:46 11 -> pipe:[14474]
l-wx------ 1 root root 64 Jun 26 15:46 12 -> pipe:[14474]
lrwx------ 1 root root 64 Jun 26 15:46 13 -> /proc/xen/privcmd
lrwx------ 1 root root 64 Jun 26 15:46 14 -> /dev/xen/evtchn
lrwx------ 1 root root 64 Jun 26 15:46 15 -> /dev/xen/gntdev
lrwx------ 1 root root 64 Jun 26 15:46 16 -> /dev/ptmx
lrwx------ 1 root root 64 Jun 26 15:46 17 -> /dev/xen/evtchn
lrwx------ 1 root root 64 Jun 26 15:46 18 -> /dev/xen/evtchn
lrwx------ 1 root root 64 Jun 26 15:46 19 -> socket:[15403]
l-wx------ 1 root root 64 Jun 26 15:46 2 -> /var/log/xen/qemu-dm-test-01.log
lr-x------ 1 root root 64 Jun 26 15:46 20 -> pipe:[15405]
l-wx------ 1 root root 64 Jun 26 15:46 21 -> pipe:[15405]
lrwx------ 1 root root 64 Jun 26 15:46 25 -> /var/run/xend/dm-4-1403189404.fifo
lr-x------ 1 root root 64 Jun 26 15:46 3 -> pipe:[14469]
l-wx------ 1 root root 64 Jun 26 15:46 4 -> pipe:[14469]
lrwx------ 1 root root 64 Jun 26 15:46 5 -> /proc/xen/privcmd
lrwx------ 1 root root 64 Jun 26 15:46 6 -> /proc/xen/xenbus
lrwx------ 1 root root 64 Jun 26 15:46 7 -> /dev/ptmx
lrwx------ 1 root root 64 Jun 26 15:46 8 -> /var/run/tap/qemu-read-4
lrwx------ 1 root root 64 Jun 26 15:46 9 -> /var/run/tap/qemu-write-4




-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxx] 
On Behalf Of Ian Campbell
Sent: Thursday, June 26, 2014 2:58 PM
To: Stephan Viljoen
Cc: xen-users@xxxxxxxxxxxxx
Subject: Re: [Xen-users] Lost images..

On Thu, 2014-06-26 at 14:41 +0200, Stephan Viljoen wrote:
> I just made one hell of screw up by accidently deleting the wrong 
> folder containing all my xend domain images. Now the strange part is , 
> all those hosts are still alive and thankfully Iâm able to make 
> backups for the content so I was wondering whether thereâs a way to 
> somehow restore the images?

If this were happening with normal processes (i.e. you've deleted a file which 
some process has open) then you'd be able to recover it via /proc/$PID/fd.

So if the domains are using a userspace process as a disk backend (e.g.
tapdisk or qdisk) then you could probably apply that technique to the backend 
processes.

If the domains are using loop+blkback then I guess you might find the content 
in /dev/loop*.

If the domains are using just blkback directly then I think you might be stuck, 
or at least I don't know what to suggest. You said folder of images so I'm 
hopeful you don't fall into this case.

Ian.




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