Rahul,

You're dumping to a remotely attached linear tape drive.

I have seen this kind of thing many times with DLT drives (of all flavours).

If the network link can't quite keep up with the drive for a moment due to other network loads (or lots of seek on the filer due to large number of inodes), the drive stops and rewinds ("backhitching"). The time it takes to do this is hundreds of times longer than the momentary network congestion, so this plays havoc with the I/O queuing on the host the tape is attached to, which causes "dump" on the filer to back off and wait because it's not getting RMT verifies. This results in even more sporadic gaps in the stream to the tape drive, which backhitches more....

i.e. you end up in a vicious circle of performance degradation. The speed variance available in SDLT is not enough to prevent backhitching.

The cures:

1) Attach the tape drive to the filer!

2) Provide dedicated bandwidth for the backup - i.e. a crossover gigabit link between the Sun box and the filer. (private subnet IP range as well of course)

3) Replace the SDLT with a non-linear tape that doesn't backhitch - i.e. AIT3 or VXA2. AIT3 is IMHO superior to SDLT in many ways.

All of these options will cost you money - even (1) if you need to then buy NetVault so you can backup all the other servers' local disks to the tape attached to the filer. But obviously budget is a problem or you wouldn't be using dump.

Hope this helps.

Alan.

-----Original Message----- From: Kumar, Rahul [mailto:rahul.kumar@eds.com] Sent: Tuesday, 10 December 2002 5:58 PM To: toasters@mathworks.com Subject: Dump issue Importance: High

Hi

Any Ideas why the dump is running so slow. We are running the filer to dump onto a SDLT tape drive

DUMP: creating "/vol/vol0/../snapshot_for_backup.0" snapshot. DUMP: Using Full Volume Dump DUMP: Dumping tape file 1 on /tmp/filer1tape DUMP: Date of this level 0 dump: Mon Dec 9 23:02:06 2002. DUMP: Date of last level 0 dump: the epoch. DUMP: Dumping /vol/vol0/ to root DUMP: mapping (Pass I)[regular files] DUMP: mapping (Pass II)[directories] DUMP: estimated 44482138 KB. DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] DUMP: Mon Dec 9 23:08:37 2002 : We have written 328738 KB. DUMP: Mon Dec 9 23:13:37 2002 : We have written 813336 KB. DUMP: Mon Dec 9 23:18:37 2002 : We have written 1248349 KB. DUMP: Mon Dec 9 23:23:37 2002 : We have written 1780575 KB. DUMP: Mon Dec 9 23:28:37 2002 : We have written 2307507 KB. DUMP: Mon Dec 9 23:33:37 2002 : We have written 2782586 KB. DUMP: Mon Dec 9 23:38:37 2002 : We have written 3220125 KB. DUMP: Mon Dec 9 23:43:37 2002 : We have written 3751844 KB. DUMP: Mon Dec 9 23:48:37 2002 : We have written 4190113 KB. DUMP: Mon Dec 9 23:53:37 2002 : We have written 4641781 KB. DUMP: Mon Dec 9 23:58:37 2002 : We have written 5080513 KB. DUMP: Tue Dec 10 00:03:37 2002 : We have written 5606338 KB. DUMP: Tue Dec 10 00:08:37 2002 : We have written 6088137 KB. DUMP: Tue Dec 10 00:13:37 2002 : We have written 6572608 KB. DUMP: Tue Dec 10 00:18:37 2002 : We have written 7016947 KB. DUMP: Tue Dec 10 00:23:37 2002 : We have written 7542679 KB. DUMP: Tue Dec 10 00:28:37 2002 : We have written 7984060 KB. DUMP: Tue Dec 10 00:33:37 2002 : We have written 8503801 KB. DUMP: Tue Dec 10 00:38:37 2002 : We have written 8958353 KB. DUMP: Tue Dec 10 00:43:37 2002 : We have written 9390217 KB. DUMP: Tue Dec 10 00:48:37 2002 : We have written 9828824 KB. DUMP: Tue Dec 10 00:53:37 2002 : We have written 10260501 KB.

Rahul

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