On 5/10/23 21:49, Dr. Thorsten Brandau wrote:
Hi I use an lto-9 drive for backup. I activated hardware compression on the tape (i think) but all the logs of bacula show a tape change at 18TB which should be the native (uncompressed) capacity. From experience I would expect a ratio of at last 1:1.2. Is there any way to make sure to use compression (or as last resort activate software compression)?
Hello Thorsten, Of course, with LTO tape drives, you always want to enable hardware compression and disable software compression in Bacula. How that is set on your specific drive(s) I do not know. :)Bacula will just write until it gets an EOT (end of tape) from the tape drive, so the compression you will see is dependent on your dataset.
Some tips:In your Director's configuration for the Storage resource which points to the SD's Tape drive (or library with multiple drives), you should set
`AllowCompression = no`This will tell the FDs to not try to compress data before sending it to the SD when using this Storage resource in a job, even if you have a `compression = (lzo|gzip|zstd)` in your fileset.
For jobs using this Storage, if compression in enabled for the fileset in use, you will see a harmless info log entry in the job logs telling you that "compression is not allowed for this storage device". (or similar)
I prefer to enable/disable this in the Director's Storage resource and always enable compression in my filesets so that the same job and fileset, when using a different Director Storage that allows compression, it will automatically "Just Work"™
P.S. You can enable/disable compression in the SD's Devices, but I prefer to set it at what I would call the beginning of the chain in the Director's Storage resource.
Home some of this is helpful, Bill -- Bill Arlofski w...@protonmail.com
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