Showing results for 
Search instead for 
Did you mean: 


Occasional Visitor


Hello All,

Can anybody confirm me that fbackup taken through SAM is compressed or not.

If not is there any option expect from hardware.


Paramvir Bhardwaj
V. Nyga
Honored Contributor

Re: Fbackup


it depends to your configuration.
Compression is only set by choosing the right device file.
Check /dev/rmt:
Ending with 'BEST' is with compression.
Either you choose this one in SAM or see if '0m' is configured like '*BEST'.
For example at my server:
crw-rw-rw- 2 bin bin 205 0x020000 23. Juli 2004 0m
crw-rw-rw- 2 bin bin 205 0x020000 23. Juli 2004 c2t0d0BEST

So I can choose either c2t0d0BEST or 0m, both will compress.

crw-rw-rw- 1 bin bin 205 0x020001 23. Juli 2004 c2t0d0DDS - will not compress.

*** Say 'Thanks' with Kudos ***
Bill Hassell
Honored Contributor

Re: Fbackup

As mentioned, fbackup does not control compression, the device file enables compression. There are very few device files in /dev/rmt that are NOT setup for compression. To see the options for each device file, use lssf:

lssf /dev/rmt/*

If you are using /dev/rmt/0m, then it is compressed -- the words "best density available" means that this device file will enable compression. NOTE: compression is only effective with highly repetitive patterns such as massively large text files and partially filled databases. A backup of just vg00 will average about 1.2:1 to 1.6:1 compression, nowhere near to the 'marketing' value for tape drives which is 2:1. If you plan for the only native capacity of the tape, then you won't be disappointed.

Bill Hassell, sysadmin
Occasional Visitor

Re: Fbackup