Re: [Duplicity-talk] Duplicity 4.2.1 on CentOS 4.7 causing resource shortage on VPS

[Kenneth Loafman]

Marcus Clements wrote:
> Hi,
> 
> I am happily using Duplicity 4.2.1 on my CentOS 4.7 VPS as a scheduled
> nightly backup. Here are the statistics from last night (a typical
> night):
> 
> --------------[ Backup Statistics ]--------------
> StartTime 1236141154.58 (Wed Mar  4 04:32:34 2009)
> EndTime 1236142613.88 (Wed Mar  4 04:56:53 2009)
> ElapsedTime 1459.30 (24 minutes 19.30 seconds)
> SourceFiles 274433
> SourceFileSize 11725383817 (10.9 GB)
> NewFiles 439
> NewFileSize 257124568 (245 MB)
> DeletedFiles 235
> ChangedFiles 1347
> ChangedFileSize 447798267 (427 MB)
> ChangedDeltaSize 0 (0 bytes)
> DeltaEntries 2021
> RawDeltaSize 133981593 (128 MB)
> TotalDestinationSizeChange 276740588 (264 MB)
> Errors 0
> -------------------------------------------------
> 
> I use munin to monitor the performance of the server in general and
> there are no unusual or troubling resource problems reported there.
> However in the Virtuozzo control panel, under Quality of Service,
> every night during the backup the VPS runs out of lockedpages, which
> are (from the Virtuozzo manual) "The memory not allowed to be swapped
> out (locked with the mlock() system call), in pages."
> This server is relatively new and not under much load currently but
> that is likely to change in the coming months. I've talked to the
> hosting provider, who doubled the lockedpages parameter a couple of
> days ago in response to my request but QoS still repeatedly reports
> "Yellow Zone", "Red Zone" and "Black Zone" resource shortages for
> lockedpages.
> 
> I'm concerned that the backup will make the server run slowly while it
> is in operation. Is there a change I can make to the settings in
> Duplicity or elsewhere in the system so that the process uses less of
> the lockedpages resource?

You're running an ancient version of duplicity, so I would first suggest
you upgrade to the latest, 0.5.10, before doing much more analysis.  You
can get the newest version at http://duplicity.nongnu.org/.

As to mlock'ed pages -- duplicity does not explicitly lock any pages
into memory, so I am going to have to ask what command line you used,
and what is the target filesystem (Linux or Windows), and any other
details you can give (Python version, etc.).

...Thanks,
...Ken

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