Topic: DDS4 tape backup is slooow

[Peter Walter]

I recently converted a Dell PowerEdge 1300 box (700 Mhz / 256Mb) from M$ to E-Smith. The box contains a Dell Powervault 100T SCSI-2 DDS4 20GB drive with a spec of 2.4MB/sec backup throughput. The throughput spec was acheivable under Windows; however, under a stock E-Smith 5.5 config, the average backup rate is only 702KB/sec, using the stock backup panel. Can anyone suggest how the backup performance under E-Smith can be increased?

[Paul Isaacs]

Hi Peter,

I have just updated the system to a DLT7000. It started off with a slow backup, but I altered the buffer size from 10k (default) to 64k, and dropped from 5 hours to 1.5 hours.
I tried 32k on the way, but 64k worked best for me. Aparently its tape drive specific.

For my version of e-smith I altered this in:
/etc/flexbackup.conf

for later versions there appears to be a server manager module to do this:
http://mirror.contribs.org/smeserver/contribs/dmay/mitel/contrib/flexbackup/

Worked for me, good luck,

Paul

[Peter Walter]

Paul,

Thank you very much for your suggestion. I loaded  Darrel's flexbackup rpm (God bless Darrell - if he did not exist, he would have to be invented) and tried a buffer size of 32k, and got a marginal improvement. I will try 64k next.

Peter

[Peter Walter]

Additional information ... a 64K buffer size (set in Darrel May's flexbackup panel) did not seem to help much, either.  A careful reading of the email message produced by the backup script indicated that the script was still using a 10k buffer size! I tracked dow this problem to the 10Blocksize fragment in /etc/e-smith/templates-custom/etc/flexbackup.conf , an excerpt of which follows:

{
my $blksize = db_get_prop(\%conf, "flexbackup", "blksize");

if (defined $blksize)
.....
it appears that $blksize is not being properly set to the data entered into the flexbackup panel. Can anyone suggest how to fix this?

Peter