cron fbackup vs Sam Interactive backup

[otukile]

I have data of more than 40G. I use a DLT4 tapes on a DLT8000 stand alone drive.

When i do backup using SAM interactive backup, backup is succesful. When i do fbackup using crontab, i am asked for more media to do backup.

I need clarification on why this is so. Does SAM IB use compresion while cron/fbackup does not? Or how else.

ANy help in shedding light on this would be apreciated.

[Johnson Punniyalingam]

Hi ,

>>I need clarification on why this is so. Does SAM IB use compresion while cron/fbackup does not? Or how else.<<



SAM uses fbackup and does not do anything special. Now as is true with all backup programs, there are headers for each file and for fbackup, a compete index of everything that was saved. This can be a very large file if your system has 100's of thousands of files. This index is very desirable but not found in tar or cpio or and of the classic Unix backups. Ineed, fbackup is the closest you can get to a commercial-quality backup program. Not only does every tape have an inde, but any file can be retrieved in just a few minutes fbackup has error recovery in case of a bad spot, it has changer capability, and most important, it supports all file sizes (hundreds to thousands of Gb).

So the first thing to do is to earn the command line options--and most important, always use a config file (-c config-file). Otherwise, you'll waste a lot of tape and the backup will take a lot longer. The config file looks like this:

blocksperrecord 512
records 64
checkpointfreq 1024
readerprocesses 6
maxretries 5
retrylimit 5000000
maxvoluses 200
filesperfsm 2000

Then use the -i and -e options as needed and try your backup again. Note also two very useful commands:

frecover -V - -f /dev/rmt/0m

(for a header listing)

frecover -I /tmp/myindex -f /dev/rmt/0m

For a complete index. And as always, very that the tape device file you are using reports "best density" using the lssf command.

Thanks,
Johnson

[Johnson Punniyalingam]

Very important: Neither SAM nor fbackup (or tar or cpio, etc) do compression. You enable compression by using the correct device file. When you run fbackup, what is your -f parameter? Then run lssf against that device file. For example:

lssf /dev/rmt/0m
stape card instance 2 SCSI target 0 SCSI LUN 0 at&t best density available at ad
dress 10/12/5.0.0 /dev/rmt/0m

The above indicates that this particular device will use compression ("best density").


Thanks,
Johnson