A> On Fri, Sep 19, 2008 at 12:57:25PM -0400, Bill Holland wrote:
You can use 'mt' to mount a tape, enable diagnostics, and some rudimentary testing of the device. If you are using ndmp to perform the restore, you can enable debugging ('ndmpd debug 70' for max info) to see if there are any issues there.
A> Yeah. Tape motion works fine. I just wanted to see if I could A> direct OnTap to read the tape rather than deal with netbackup.
Did you enable DAR with your NDMP backups? As I understand it, DAR allows the backup software to move the tape to the closest position near the file to be restored, which makes things much faster. Otherwise it needs to scan the tape sequentially...
A> While netbackup/NDMP is restoring the file, I see very slow reads A> on sysstat, but I don't know if that's an NDMP issue or a tape read A> issue.
Hmmm.... does NetBackup use a really small block size?
Maybe NDMP copy could be used to try and pull the backup off tape and send it to another node where you can extract it via pipe to tar (or whatever NetBackups uses for it's internal format) that way?
sysstat could be helpful during the restore to try to determine any bottlenecks on the filer end. Also, the syslog for any SCSI
Restores will be slower than backups. I don't know the max's for the FAS6070, but when we had an R200 we saw that we could run about 200MB/sec backups with the CPUs at 100%.
A> I can't get near that on the LTO-3. I never get faster than A> 80MB/s. The restore is around 100 KB/s.
That's just way too slow. I assume it's a fibre channel drive? All the way down to the drive? You'd think even a plain read/scan of the tape would fly.
What happens if you create your own backup tape(s) on the filer using plain 'dump' commands to the same drive. Can you then read it back more quickly? That will at least give you more confidence that you've got a good connection.
Speaking of that, maybe you've got a flaky fibre connection or dirty optics? Try re-seating both ends of the cable to make sure you're getting the right connection. I remember one with a 50pin (or was it 68?) where we bent one pin in the connector and it just failed down to old SCSI-1 speeds, but it did work. Just really really slowly...
A> CPU NFS CIFS HTTP Net kB/s Disk kB/s Tape kB/s Cache A> in out read write read write age A> 54% 803 46 0 10642 5422 19045 15465 193 0 >60 A> 18% 224 1 0 1330 5169 13065 13240 193 0 >60 A> 22% 636 0 0 7691 6498 18857 12320 64 0 >60 A> 20% 673 0 0 8540 6608 23073 19397 129 0 >60 A> 29% 501 0 0 7063 5842 14262 29822 64 0 >60 A> 24% 520 105 0 11136 5959 15357 4519 258 0 >60
A> I'm actually trying to restore a single 100K file. I assume that it has A> to read through some of headers at the beginning of the tape, but it was A> sure slow doing it.
A> -- A> Darren