LTO-3/4 hardware vs. software compression

[RalfG]

Hi,

I'm using a backup programm that allows to use disk and tape based backups (bacula on linux debian). Until now I only backed up to tape (LTO-3 + LTO-4). Now I want to use backup2disk for the incremental and differential backups. The programm is able to compress data with gzip, and I want to use this option. But this can only be enabled on a job basis. So it would also be enabled for full backups on the LTO-3/4 tapes.

As far as I know, it's not a good idea to use software- and the drives hardware compression together (data may get bigger on tape). But I also heard that recent drives can detect compressed data and that the negativ effect of sw + hw compression will not be that bad.

So, should I disable the drives hardware compression when using gzip compression?

Will older tapes with enabled hw compression then still be readable?

[Curtis Ballard]

HP LTO tape drives won't expand compressed data when they write so it shouldn't be a problem. The main difference is that it will use a lot more host resources and the compression process may slow down the backup.

The drive will still read compressed tapes just fine.

[RalfG]

I'm spooling data before writing to tape so the extra overhead for compression won't affect the speed tape write speed.

The extra load on the clients won't be a problem too.

So I'll leave hw compression enabled. Thanks.