Userspace cp and ls utility

Userspace cp and ls utility

[Jan Dittmer]

Are there utilities for xfs which are able to ls and
cp from an _unmounted_ xfs volume? I fear that by
mounting the volume - even ro - I would lose even more
data.
Or can I achieve such an effect with other xfs related
utilities?

Thanks,

Jan

Re: Userspace cp and ls utility

[Eric Sandeen]

Jan Dittmer wrote:
> Are there utilities for xfs which are able to ls and
> cp from an _unmounted_ xfs volume? I fear that by
> mounting the volume - even ro - I would lose even more
> data.
> Or can I achieve such an effect with other xfs related
> utilities?

Mounting ro should be fine - if you also mount with "norecovery" then truly no 
IO should happen.  If you're really paranoid, find a utility to mark the block 
device itself as read-only, then you've taken it out of the filesystem's hands 
completely.

You could also try xfs_copy, it makes a copy of the filesystem and works on the 
underlying device, with the filesystem unmounted.  There's a man page for it.

-Eric

Re: Userspace cp and ls utility

[Jan Dittmer]

Eric Sandeen schrieb:
> Jan Dittmer wrote:
> 
>> Are there utilities for xfs which are able to ls and
>> cp from an _unmounted_ xfs volume? I fear that by
>> mounting the volume - even ro - I would lose even more
>> data.
>> Or can I achieve such an effect with other xfs related
>> utilities?
> 
> 
> Mounting ro should be fine - if you also mount with "norecovery" then 
> truly no IO should happen.  If you're really paranoid, find a utility to 
> mark the block device itself as read-only, then you've taken it out of 
> the filesystem's hands completely.

Thanks for the suggestions. Meanwhile I found the norecovery option
myself and got most of my data back. Strangely enough I had one top
directory missing on one mount attempt (only ro option) and it appeared
again on the next attempt (ro + norecovery).

> You could also try xfs_copy, it makes a copy of the filesystem and works 
> on the underlying device, with the filesystem unmounted.  There's a man 
> page for it.

Is there any difference to using dd when the destination is no xfs
filesystem? And if I read the description correctly it does not allow
to copy individual files?

Thanks,

Jan

Re: Userspace cp and ls utility

[Eric Sandeen]

Jan Dittmer wrote:
>> You could also try xfs_copy, it makes a copy of the filesystem and 
>> works on the underlying device, with the filesystem unmounted.  
>> There's a man page for it.
> 
> Is there any difference to using dd when the destination is no xfs
> filesystem? And if I read the description correctly it does not allow
> to copy individual files?

xfs_copy knows about the xfs format, so it only copies what it needs to.  dd 
will copy every bit on the source disk.  So, xfs_copy is more efficient.  There 
is no option to copy individual files.

Depending on the problem with your original filesystem, perhaps xfs_copy might 
not be the best choice.

-Eric

Re: Userspace cp and ls utility

[Jan Dittmer]

Eric Sandeen schrieb:
> Jan Dittmer wrote:
> 
>>> You could also try xfs_copy, it makes a copy of the filesystem and 
>>> works on the underlying device, with the filesystem unmounted.  
>>> There's a man page for it.
>>
>>
>> Is there any difference to using dd when the destination is no xfs
>> filesystem? And if I read the description correctly it does not allow
>> to copy individual files?
> 
> 
> xfs_copy knows about the xfs format, so it only copies what it needs 
> to.  dd will copy every bit on the source disk.  So, xfs_copy is more 
> efficient.  There is no option to copy individual files.
> 
> Depending on the problem with your original filesystem, perhaps xfs_copy 
> might not be the best choice.

Well I suffered from the 2.6.17 endian bug and had fun with dis- and re-
appearing folders upon xfs_repair and mount runs.
After all the 'only' thing I lost from my 600+gb volume are one or two
mailing list folders and most of my inbox (for which I've backups).
Seems to only affect folders which were open at the wrong moment.

Now I reformated the whole volume and restore the data from other
disks.

Jan