Re: DLT Backup/Restore Speed

From: Mike Brown (mike_at_tkg.ca)
Date: 12/30/04 

Date: Thu, 30 Dec 2004 11:07:44 -0500

JP wrote:
>
> We found the speed for backup and restore quite slow on the HP Netserver
> LH3000 runnign SCO 5.0.6. The tape drive is an HP SCSI-3 DLT 40/80
> connected to an Adaptec Ultra 160 controller.
>
> To backup and verify 70GB of data on the RAID (0+1) drive, it took 7 hours.
> Just to restore 2 files of 100MB each this afternoon, it took 2 hours each.
> When compared with the performance of the backup/restore on another Windows
> server, it is very hard to justify the slow speed. I can restore a 100MB
> file in just 15 minutes using BackupExec.
>
> I am not sure it is the right speed for our tape storage on the SCO. We are
> running BackupEdge version 01.0.08, build edgesco5.01.01.08. Here is the
> configuration of the tape:
>
> Device Nake: dev/rStp0
> Compression: Hard
> Tape Block: N/A
> Edge Block: 64
> Partition: C
>
> Can someone tell me if this is the right speed or something can be done to
> improve the speed? Thanks in advance.
>
> Joe

The speeds you are seeing are normal, depending on the drive and compressability
of the data. Using the HP DLT VS80 on a ML530 I see a 38.76 Gbyte backup in
3:43:55, or about 180.17 MB/min. The VS80 version is rated at 3MB/sec to the
tape, or about 6MB/sec with 2:1 compression overall. Some of the DLT drive
run at double this speed, check the specs on yours.

If I assume 1/2 the time for a backup, you have a throughput rate of around
6MB/sec to the tape drive. What does the Edge summary file say?

Your best bet for overall speed is to upgrade to the current version of BackupEdge,
02.00.03. Configure it for software compression ( which will turn off the drives
compression ) and play with the tape block size, try 128 first.

Are you indexing the backup and using Microlites FFR?

Mike 

-- 
Michael Brown

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