Am 08.04.25 um 14:18 schrieb Gilles Van Vlasselaer:

Hi all, I'm having issues with write speeds to our LTO drive. Copy jobs aren't 
going over 100 MB/sec, and on average it's around 80 MB/sec.

Using btape speed I was benchmarking the performance on different tapes (HW 
compression on/off, HW encryption on/off), and it reached 180-220 MB/sec, 
depending on the test. Still, it's nowhere near the theoretical maximum of the 
LTO 8 specification. But even reaching the benchmark speeds would mean that our 
job copy time would be halved.

Our Storage Daemon stores all full and incremental backups on a file volume. 
This volume resides on a ZFS pool. I've also benchmarked the ZFS pool, and it 
easily reads continuously over 300 MB/sec. Once a month, we issue a Copy Job to 
the LTO 8 tape.

Bacula DIR and SD run on the same machine, with a Quantum LTO-8 HH drive, using 
Quantum MR-L8MQN-01 tapes.


Am I'm missing some important properties in the resources? Any help is 
appreciated.

- Gilles



Hi Gilles,

Your Maximum File Size ist too small. If you assume 300MB/sec the tape would 
stop every 5000/300 seconds to write an EOF mark. That cannot be fast. Please 
try at least the amount of data for writing 3 minutes sustained (Maximum File 
Size = 54GB).
Be aware that you have to wait at least for one complete block to be read if 
you are doing a restore. (3 minutes again in our example). What size are your 
file volumes?

Best regards, Udo

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