[Box Backup] Housekeeping hogging the server

[Per Thomsen]

On 10/20/06 2:13 PM, Jan Rychter wrote:
> Hi,
>
> I've been using boxbackup for a while and it is a great
> application. Many thanks to the authors for such a wonderful tool!
>
> I have one annoyance, though: bbstored does its housekeeping, which in
> my case both consumes a lot of CPU time and does a lot of I/O, which
> slows the server machine down a lot.
>
> Is that much housekeeping really needed? Is there any way to reduce the
> load on the server?
>   
A bit of explanation: The housekeeping process keeps the accounts within
their respective limits for the amount of backed up data. To do that, it
needs to check which files are the oldest, and get rid of them from the
store. This takes CPU and I/O.

One thing you can do is to increase the time between housekeepings. That
will lower the incidence of the problem, but will likely make it take
longer when it does occur.

The parameter in bbstored.conf is TimeBetweenHousekeeping. The default
setting is 900 seconds (15 mins).

I would maybe try 3600 (1 hour) to see if things feel better.

Unfortunately, you can't do without the housekeeping, but maybe this
will help. I have not tried changing this parameter, so I don't know
what the effects are.

On my old backup server, I was seeing load-averages around 3 or so (on a
single-CPU machine) when the housekeeping was purging files over the
limits. This did not occur every 15 minutes, but only when an account
had hit its hard limit.

Another thing that might change the behavior is to increase difference
between the soft limit and hard limits for your client accounts. This
would help reduce the number of times a client would hit the hard limit,
and housekeeping would need to purge files. Of course, the downside to
this is that when the hard limit is hit, there's a bigger amount of
purging to do.

The command for this is 'bbstoreaccounts setlimit'. The documentation
describes the command, so I'm not going to duplicate it here.

HTH,
Per

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Per Reedtz Thomsen | Reedtz Consulting, LLC | F: 209 883 4119
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