Tape drive performance 1

[nashcom]

I'm just finalising our changeover of a SCO OpenServer 5.0.0 system from an old Digital server to a newer Comaq one. The Digital server had a Sony DDS DAT drive - one of the original 2/4GB drives. When doing a full cpio backup of the /root filesystem, it took around twenty to thirty minutes. The Compaq server has a later DDS3 12/24GB tape drive. With the same data (that was transferred from the old server), it's taking around forty-five minutes to back up. Moreover, when I tested a disaster recovery on the Compaq server by installing a blank HDD, booting from the emergency floppies, and then doing a cpio restore, the restore took somewhere in the region of two hours! I can't check the validity of the backups without some additional software such as BackupEdge, but it certainly seemed to restore okay with no corruptions. When backing up it seems to whizz through the files fairly quickly, but seems to take an inordinate amount of time to backup larger files. The jumper and dip switch configurations are the same between the two DDS drives, we're using new tapes, and I didn't do anything with mkdev to add the larger capacity tape drive. Could it be something to do with blocking factors? It's backing up around 650MB (in 45 mins) using the following cpio command from /

find . -depth -print | cpio -ocv > /dev/rmc0

 

[PHV]

You may try this command before the backup and before the restore:
tape -a 1024 setblk

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244

 

[nashcom]

Wow! That's great! Thanks PH - it backed up in 6.5 minutes (instead of 45)!

BTW what's the 'correct' way to add this command to the startup configuration? Is it better to add to the root user profile, or in some sort of rc.d script (that I can never remember how to do), or is there a better way?

 

[PHV]

The safer way is to include it in your backup/restore script(s).

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244