On 7/27/2011 2:42 PM, C. Ronoz wrote:
>
>> What is the CPU utilization during the BackupPC backup? What is the
>> network utilization? What is the disk utilization? Is the machine
>> swapping? Is it doing something else?
> The CPU utilization used to be very high until I disabled gzip compression
> last week. This did not affect performance, just processor usage. The machine
> is not swapping and has free memory even. The server i
> s a clean CentOS install with minimal packages installed, although on Debian
> the server did not perform better. I have installed packages via 1) EPEL and
> 2) Debian repository.
>
> During back-ups the load often goes up to an average of 2 or 3,
> cpu-utilisation is still somewhat high, although much lower than before
> disabling gzip compression.
Note that compression only happens on the initial copy of a file. If it
is unchanged on the next full the server will uncompress for the
block-checksum verification (but uncompressing is fairly fast), then if
you have checksum caching enabled it will store those checksums so on
the 3rd and subsequent fulls the server side doesn't have to recompute
them at all. And incrementals will skip the content check if the file
length and timestamp matches.
>> We've been trying to tell you that you're seeing abnormal performance. I
>> get much better performance with a single 1.5GHz VIA processor, 512MB RAM
>> and a single SATA spindle. Something is wrong here. We are not going to
>> be able to tell you what: you will have to dig a little deeper and see
>> what your machine is doing during a backup.
> Yes, I seem to be poor at troubleshooting bad performance with BackupPC.
After the 1st run, MB/sec isn't a good metric when using rsync xfers.
Mine show everywhere between 1.02 to 13.91.
> The server has enough RAM for sure. There are a lot of tiny files, but only
> because BackupPC is said to back-up all files/directories starting from /. A
> fresh CentOS/Debian install seems to have already 30.000 files. The most
> crowded server has 200.000 files.
Those aren't particularly big numbers - if you have millions it might be
an issue.
--
Les Mikesell
[email protected]
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