Hi,

I'm using BackupPC without major problems since a few years now. Our
main fileserver has now reached 3,3 TB and it takes 2 days (18 MB/s)
to do a full backup with tar method.

I'd like to find out if there is something I can do to speed up the full
backups without changing the hardware.

The file server and the BackupPC server are connected by Gigabit Ethernet
links. The BackupPC pool is on a harware raid device (RAID6) with 1 GB
cache. The setup of the file server is a bit complex with drbd/lvm....

Both server are running debian with xfs as filesystem.

I'd have expected high iowait numbers during backup, either on the file
server or the BackupPC side. But the numbers look ok, not too much iowait.


BackupPC server:

04:35:01  CPU  %user     %nice   %system   %iowait    %steal     %idle
04:45:01  all  37.97      0.00      7.29     10.86      0.00     43.88
04:55:01  all  35.87      0.00      5.32      9.11      0.00     49.70
05:05:01  all  34.69      0.00      4.96      9.91      0.00     50.44
05:15:02  all  41.40      0.00      5.88      6.22      0.00     46.50
05:25:01  all  44.81      0.00      6.14      4.18      0.00     44.87
05:35:01  all  39.34      0.00      5.41      8.41      0.00     46.84
05:45:02  all  44.90      0.00      6.84      3.59      0.00     44.68
05:55:02  all  32.12      0.00      5.87      5.90      0.00     56.12
06:05:01  all  34.23      0.00      6.32      6.28      0.00     53.17
06:15:02  all  30.66      0.00      6.01      7.31      0.00     56.01
06:25:01  all  18.76      0.00      3.69      7.38      0.00     70.17
06:35:03  all  22.08      0.00      5.27      6.61      0.00     66.04
06:45:01  all  39.50      0.00     11.54      0.37      0.00     48.59
06:55:01  all  37.16      0.00      9.91      2.18      0.00     50.75
07:05:02  all  24.52      0.00      4.99      8.99      0.00     61.50
07:15:01  all  11.46      0.00      2.65     13.12      0.00     72.77
07:25:02  all  11.65      0.00      3.16     11.16      0.00     74.03
07:35:01  all  25.32      0.00      5.48      7.22      0.00     61.97
07:45:01  all  26.68      0.00      6.71      6.99      0.00     59.62
07:55:02  all  29.74      0.00      5.80      4.08      0.00     60.38
08:05:01  all  42.30      0.00      6.34      3.49      0.00     47.87
08:15:01  all  18.21      0.00      4.26     21.14      0.00     56.39
08:25:01  all  25.73      0.00      5.32     20.17      0.00     48.78
08:35:01  all  34.94      0.00      6.42      5.61      0.00     53.03
08:45:02  all  26.25      0.00      5.00     10.71      0.00     58.04
08:55:01  all  48.16      0.00      8.18      0.53      0.00     43.14
09:05:01  all  44.54      0.00      7.10      2.25      0.00     46.11
Average:  all  29.70      0.00      5.48      8.36      0.00     56.46

file server:

06:25:01  CPU  %user     %nice   %system   %iowait    %steal     %idle
06:35:01  all   5.91      0.10      7.25      5.71      0.00     81.03
06:45:01  all   6.08      0.00      9.49      4.91      0.00     79.52
06:55:01  all   5.71      0.00      8.72      3.91      0.00     81.65
07:05:01  all   5.67      0.00      6.89      4.16      0.00     83.28
07:15:01  all   5.59      0.00      5.72      5.89      0.00     82.79
07:25:01  all   5.24      0.00      9.86      6.27      0.00     78.62
07:35:01  all   5.91      0.00     13.82      5.10      0.00     75.17
07:45:01  all   5.10      0.00      7.54      4.82      0.00     82.55
07:55:01  all   4.35      0.00      6.69      3.53      0.00     85.43
08:05:01  all   1.77      0.00      3.57      2.17      0.00     92.49
08:15:01  all   1.81      0.00      2.44      3.73      0.00     92.02
08:25:01  all   2.10      0.00      4.75      3.08      0.00     90.07
08:35:01  all   2.10      0.00      6.37      3.60      0.00     87.92
08:45:01  all   2.31      0.00      5.09      3.46      0.00     89.15
08:55:01  all   2.05      0.00      4.06      1.34      0.00     92.56
09:05:01  all   2.00      0.00      3.63      2.31      0.00     92.06
Average:  all   2.50      0.00      3.84      2.91      0.00     90.75


After all I've read, switching to rsync instead of tar doesn't seem to be a
better choice.

Disk I/O on the file server doesn't seem to be the bottleneck either. I can
boost the disk I/O during backup with other tools (dd, cat, bonnie++) to more
than 50 MB/s.

Any ideas if I can tune my BackupPC settings to speed things up?

Ralf

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