Having just added lots of disk space to a network of Linux workstations and 
servers, I
decided to take the plunge and check out Amanda as a replacement for a set of 
home-grown
dump scripts that I have been using for years. I am moving from SuperDLT and 
backing up
10s of GB to LTO4 and wanting to back up 100s of GB.

I have been very disappointed to discover that the performance of Linux dump 
seems to be
completely awful in recent RedHat Enterprise and CentOS releases.

Have other Amanda admins seen this?

My first test dump of a 160GB filesystem (with 'program "DUMP"' in amanda.conf) 
took
~10 hours. This is completely hopeless if I want to regularly back up at least 
4 times
that amount. The poor performance is nothing to do with Amanda. It seems that 
it is
dump itself in recent Linux, eg see

 http://bugzilla.kernel.org/show_bug.cgi?id=8636

As I have a number of machines with various distributions, I have run a few 
tests of a simple

 dump -0 -f /dev/null /filesystem

with various "large" filesystem sizes. The results are summarised below. Yes, 
dump performance
has tanked. On recent RHEL and CentOS it now runs at ~8000 kB/s or less. On 
older distributions
dump is much, much faster.

I am surprised that there seems to be no earlier mention of this issue on the 
list. Do all you
Amanda admins out there use GNUTAR in place of dump on Linux?


Summary results of dump tests of ext3 filesystems on various hardware:
Disk size and type shown after distribution identity.
Dumps to /dev/null. Listed in order of decreasing performance.

Red Hat Enterprise Linux WS release 3 (Taroon Update 9) - 62G - SCSI
  DUMP: Volume 1 64051810 blocks (62550.60MB)
  DUMP: Volume 1 took 0:17:36
  DUMP: Volume 1 transfer rate: 60655 kB/s

Red Hat Enterprise Linux WS release 4 (Nahant Update 8) - 136G - SATA
  DUMP: Volume 1 141738390 blocks (138416.40MB)
  DUMP: Volume 1 took 0:51:21
  DUMP: Volume 1 transfer rate: 46004 kB/s

Red Hat Linux release 9 (Shrike) - 43G - SCSI
  DUMP: Volume 1 44403470 tape blocks (43362.76MB)
  DUMP: Volume 1 took 0:16:20
  DUMP: Volume 1 transfer rate: 45309 kB/s

SUSE Linux Enterprise Server 10 - 31G - SATA RAID
  DUMP: Volume 1 32224060 blocks (31468.81MB)
  DUMP: Volume 1 took 0:21:35
  DUMP: Volume 1 transfer rate: 24883 kB/s

Red Hat Enterprise Linux Server release 5.4 (Tikanga) - 48G - SATA
  DUMP: Volume 1 31837800 blocks (31091.60MB)
  DUMP: Volume 1 took 0:59:50
  DUMP: Volume 1 transfer rate: 8868 kB/s

CentOS release 5.3 - 95G - SCSI
  DUMP: Volume 1 98998870 blocks (96678.58MB)
  DUMP: Volume 1 took 3:25:43
  DUMP: Volume 1 transfer rate: 8020 kB/s

Red Hat Enterprise Linux Server release 5.4 (Tikanga) - 99G - SAS RAID
  DUMP: Volume 1 102944360 blocks (100531.60MB)
  DUMP: Volume 1 took 3:38:36
  DUMP: Volume 1 transfer rate: 7848 kB/s

CentOS release 5.3 - 26G - SATA RAID
  DUMP: Volume 1 26371940 blocks (25753.85MB)
  DUMP: Volume 1 took 1:06:18
  DUMP: Volume 1 transfer rate: 6629 kB/s

CentOS release 5.3 - 188G - SATA RAID
  DUMP: Volume 1 196398760 blocks (191795.66MB)
  DUMP: Volume 1 took 11:24:42
  DUMP: Volume 1 transfer rate: 4780 kB/s

--
Roger Williams, GNS Science, New Zealand : www.gns.cri.nz

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