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 Notice: This email and any attachments are confidential. If received in error please destroy and immediately notify us. Do not copy or disclose the contents.
