Backup Central

Hi,

I have set BackupPC to backup a directory where the content is always
wiped and re-populated with 99% of the time same filename and same
content inside the files. File timestamps would be different as they
have been re-generated.

I expected that BackupPC would detect it's the same filename and same
content and use hardlink instead of re-copying the file again.

However, I've been monitoring /var/lib/BackupPC/cpool using `du -sh
/var/lib/BackupPC/cpool` and it seems to be growing at a steady state
that is much faster than what I expected.

Either I am not looking at the right pool or the way I measure the pool
size (du -sh) is wrong or BackupPC is not using hardlink in my case.

To confirm my suspicions:
- is /var/lib/BackupPC/cpool the pool I need to look for
- is `du -sh` the proper way to measure the size of the pool
- how do I know how many hardlinks are pointing to the same file in the
pool?
- how do I calculate the saving ratio of using hardlink vs simple copy
the file again? (this would confirm if my instance of BackupPC is
exploiting the saving advantage of hardlink or not)

Thanks,
Long

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On 12/1/2011 3:21 PM, Long V wrote:
Hi,

I have set BackupPC to backup a directory where the content is always
wiped and re-populated with 99% of the time same filename and same
content inside the files. File timestamps would be different as they
have been re-generated.

I expected that BackupPC would detect it's the same filename and same
content and use hardlink instead of re-copying the file again.

However, I've been monitoring /var/lib/BackupPC/cpool using `du -sh
/var/lib/BackupPC/cpool` and it seems to be growing at a steady state
that is much faster than what I expected.

Either I am not looking at the right pool or the way I measure the pool
size (du -sh) is wrong or BackupPC is not using hardlink in my case.

To confirm my suspicions:
- is /var/lib/BackupPC/cpool the pool I need to look for
- is `du -sh` the proper way to measure the size of the pool
- how do I know how many hardlinks are pointing to the same file in the
pool?
- how do I calculate the saving ratio of using hardlink vs simple copy
the file again? (this would confirm if my instance of BackupPC is
exploiting the saving advantage of hardlink or not)

The simplest way to determine if hardlinks are being used is to cd into
a backup directory under /var/lib/BackupPC/pc and run 'ls -l'. The
number between the permissions string and the owner's name is the number
of hardlinks to the file. In most normal directories this number will
be 1 for almost all of the files. In a BackupPC backup directory, the
number will be at least 2 (pool and current directory) -- more if the
file is being hardlinked to other backups.

--
Bowie

------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure
contains a definitive record of customers, application performance,
security threats, fraudulent activity, and more. Splunk takes this
data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
_______________________________________________
BackupPC-users mailing list
BackupPC-users < at > lists.sourceforge.net
List: https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki: http://backuppc.wiki.sourceforge.net
Project: http://backuppc.sourceforge.net/