--On Wednesday, November 03, 2004 13:50:51 -0600 Dan Brown <monkeypants AT shaw
DOT ca> wrote:
> I've never really thought about this before until I had our DLT drive sitting
> beside our desk during some renovations. What should the average DLT1 tape
> drive perform like during backup?
> Ours happens to be a Lacie DLT1 (a Quantum DLT1 in a LaCie enclosure
> basically) which is used to backup approximately 120GB of data twice a week
> off of our two servers (~60GB each). It is attached to one of the servers.
>
> During a backup, or a flush, the tape drive writes data for 4 seconds, then
> rewinds for 1 second, then writes for 4 seconds, then rewinds for 1 second,
> etc.
> This seems like a good way to wear out a drive.
It will wear out the tapes, also. Evidently your server isn't feeding data to
the drive fast enough to keep up and the drive is constantly having to stop and
reposition itself.
>
> I also have a DDS backup drive which backs up a number of Mac machines around
> the office using Retrospect. This machine writes data in a single stream,
> and only ever seems to pause when it switches to the next machine, verifies
> data, or seeks specific
> data on a tape.
>
> Now this is a bit of a comparison of apples and oranges but should a DLT1 be
> able to write a near continuous backup stream rather than this apparent write
> 4->seek 1, write 4->seek 1 cycle during backups and flushes?
It's not the DLT that has a problem, its the server. First, make sure Amanda
is using a holdingdisk (and that it's large enough to be used so that dumps
don't need to go directly to tape). Also, consider increasing tapebufs (each
is 32k, so heed the warning in the example config before making it too large,
especially on a server with limited memory).
Frank
>
> Any suggestions on optimizing settings?
> Here are my drive configs (minus stuff about logs, users, etc):
>
> inparallel 4
> dumporder "BTBT"
> netusage 9600 Kbps
> dumpcycle 4 weeks
> runspercycle 20
> tapecycle 5 tapes
> dtimeout 1800
> ctimeout 30
> tapebufs 20
> runtapes 1
> tapedev "/dev/nst0"
> rawtapedev "/dev/null"
> holdingdisk hd1 {
> comment "main holding disk"
> directory "/var/amanda/dumps"
> use -1 Gb
> chunksize 0
> }
> reserve 45
>
> define tapetype DLT1 {
> comment "DLT1 tape drives"
> length 40960 mbytes # 40 Gig tapes
> filemark 4000 kbytes # I don't know what this means
> speed 2814 kbytes # 3.5 Mb/s
> }
>
> define dumptype high-tar-comp {
> root-tar
> comment "partitions dumped with tar, compressed with gzip"
> priority high
> compress client best
> index yes
> exclude list "/etc/amanda/exclude.gtar"
> }
>
> define interface local {
> comment "a local disk"
> use 1000 kbps
> }
>
> define interface eth0 {
> comment "100 Mbps ethernet"
> use 1000 kbps
> }
>
>
>
>
> My disklist file:
> blackhawk /clients / {
> high-tar-comp
> include "./clients"
> } 1
> blackhawk /notclients / {
> high-tar-comp
> exclude "./clients" "./tmp"
> } 1
>
>
--
Frank Smith fsmith AT hoovers DOT com
Sr. Systems Administrator Voice: 512-374-4673
Hoover's Online Fax: 512-374-4501
|
