assess tape throughput

(I also asked this in the Networker support forum)

In our quite simple environment, we are (still) doing direct backup to LTO, running Networker 8.2 on Linux (SLES11).

Does anybody know how we could properly the throughput per tape device over time, to see if the data rates match?

We tried sar, but this utility does not seem to address tape devices.

We found nsrio, but this unofficial utility is quite old.

nsrwatch has the relevant data, but cannot be redirected to a log file.

The statistics collected by Networker appear to be too inaccurate (only offering avarages over savesets or savegroups).

Should we try to measure what goes over the FC ports?

Thanks for offering a tip.

Regards, Tom

I’m not a tape expert at all, but is there a reason you cannot use ‘dd’
for this like you would for any other device/test? Assuming your tape
device is /dev/st0 (warning, will possibly wipe your tape):

dd if=/dev/zero of=/dev/st0 bs=1048576 count=1024 conv=fsync

The command above should write out 1 GiB of data to /dev/st0, and i added
on ‘conv=fsync’ in case there is a flush component to the tape device like
there is for other disk drives.

‘dd’ will give you stats information when it exits by default. Adjust the
1024 number (of MiBs) to do more or less at a time.

Good luck.

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thanks, this would help me measure what I can get at maximum, but what I need is assess the actual throughput during the nightly backups, depending on many factors (as lots of physical and virtual hosts are backed up together).