I would guess that your disk system is not fast enough to keep up with your tape drive. When this happens, it switches from streaming mode to start/stop. start/stop is very slow, and it wears out both your drive and your media. I think the DSS drive is rated at 2.5 MB/sec transfer rate. It is recommended that your disk system be 3x your tape drive speed, so your disk system needs to be at 7.5 MB/sec or faster. Try tar -cvz -f /dev/null ..... and time it. Then calculate your speed. If it is indeed your disk system, you might want to try bfr. http://www.glines.org:8000/software/buffer.html It can sit between tar and your tape drive. Since you have lots of RAM, you could setup a huge buffer and it might make things work much smoother. i.e. a 100 MB buffer should make things work really smoothly. Greg
Hi, I have a curiosity. I have a simple backup process that everyday runs late at night when no one is on this server. Yet the performance of the tar process is extremely slow at times. The maximum speed I have ever seen it go is at 6MB/second but it drops down to around 1MB/second. It can mean a difference of a 20 minutes backup to a 1.5 hour backup. The amount of data is relatively the same. It might grow 1 to 2 more MBytes. Not significant. Anyway I like to see if anyone has come accross this. The tar command is: tar -cvz -b 320 -f /dev/rmt0 --totals -T <filelist> (always the same files in list)
The device is a DSS 20/40GB HP Tape Drive with Ultra/Wide interface connected to a Ultra SCSI 3 port(160MB/s). Linux O/S is SuSE 8.0 System is a Dual Pentium 3 866Mhz - 2GB RAM - 25GB SCSI RAID - 120GB IDE Drives
Some samples of the messages from backup
----- Beginning oaksback backup to internal tape (rmt0)... Fri Jul 26 02:12:02 CDT 2002 Total bytes written: 5858099200 (5.5GB, 1004kB/s) Backup ended at Fri Jul 26 03:47:02 CDT 2002 ----- Beginning oaksback backup to internal tape (rmt0)... Tue Jul 30 02:06:07 CDT 2002 Total bytes written: 5865963520 (5.5GB, 5.0MB/s) Backup ended at Tue Jul 30 02:24:57 CDT 2002 ---- Beginning oaksback backup to internal tape (rmt0)... Wed Jul 31 02:12:29 CDT 2002 Total bytes written: 5866455040 (5.5GB, 971kB/s) Backup ended at Wed Jul 31 03:50:50 CDT 2002 ---- Beginning oaksback backup to internal tape (rmt0)... Thu Aug 1 02:10:13 CDT 2002 Total bytes written: 5867438080 (5.5GB, 1.6MB/s) Backup ended at Thu Aug 1 03:07:06 CDT 2002 ----
I hope someone can lead me to what maybe going on. Thanks,
Percy Cardenas River Oaks Furniture, Inc.
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Greg Freemyer Internet Engineer Deployment and Integration Specialist Compaq ASE - Tru64 v4, v5 Compaq Master ASE - SAN Architect The Norcross Group www.NorcrossGroup.com