SAN backups performance

[Lonie Waller]

Thanks for you help.

[Lonie Waller]

Has any one heard that LTO 3 drives are not performing as well as expected because the physical hard drives can't feed them the data fast enough?

[Alzhy]

Yes.. it is farily common and may be a glaring possiblity in your case.

IF you are sucking data out individual Filesystems - the more so.

Have you tried streaming several filesystems to a lone LTO3?

Filesystems (VxFS) on SAN Arrays and 2G FC-HBA and DirectIO or Discovered DirectIO can give you anywhere between 50-60 Mbyte/sec. but may vary depending on what (and how big) files are on the filesystem. Reading vai its RAW device can get you close to the theorethical speed of your FC for certain volume configurations.

Try doing:

dd if=/dev/vgxx/rlvolxx of=/dev/rmt/Xm bs=nn

to test your LTO Trhoughput...

[Lonie Waller]

Thanks I will give that try

[Lonie Waller]

No fimilar with the dd but it keeps giving me /dev/rmt/1m: I/O error
dd: cannot create /dev/rmt/1m

any thoughts?

[Alzhy]

Whatever device (/dev/rmt/Xxx) does DP use? Use that.

or you can find out via:

ioscan -kfnC tape

Am not familiar what device modifier to use though if it is /dev/rmt/Nm.

Of course .. be sure you have a test tape mounted i.e. via the "mc" command it it supports your ADIC..

[Lonie Waller]

This is the on DP uses

dev/rmt/1m

[Alzhy · Accepted solution]

You need to be root..
You need to have a tape mounted.
DO an ioscan -kfnC tape..