Subject: bin/19711: dump write speed incorrect after a volume failure & retry
To: None <>
From: None <>
List: netbsd-bugs
Date: 01/07/2003 01:18:09
>Number:         19711
>Category:       bin
>Synopsis:       dump write speed incorrect after a volume failure & retry
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 06 06:19:00 PST 2003
>Originator:     matthew green
>Release:        NetBSD 1.6K
people's front against (bozotic) www (softwar foundation)
System: NetBSD 1.6K NetBSD 1.6K (_splode_) #26: Sun Jan 5 02:48:50 EST 2003 sparc64
Architecture: sparc
Machine: sparc64

	when dump(8) attempts to write a tape volume but gets a write error
	(eg, due to a remote tape filling up), and it asks if you want to 
	rewrite the volume, it appears to not re-set the volume start time.
	the effect is that after a failed write, the write speeds are typically
	much lower than they should be, and slowly rise up.  eg:

	  DUMP: Volume 4 transfer rate: 845 KB/s
	  DUMP: Change Volumes: Mount volume #5
	  [ .. ]
	  DUMP: write: Input/output error
	  DUMP: write error 727840 blocks into volume 5
	  DUMP: Do you want to restart?: ("yes" or "no") yes
	  DUMP: Closing this volume.  Prepare to restart with new media;
	  DUMP: this dump volume will be rewritten.
	  DUMP: Closing /dev/nrst0
	  DUMP: close: Input/output error
	  DUMP: Volume 5 completed at: Tue Jan  7 00:28:21 2003
	  DUMP: Volume 5 took 1:04:49
	  DUMP: Volume 5 transfer rate: 187 KB/s
	  DUMP: Is the new volume mounted and ready to go?: ("yes" or "no") yes
	  DUMP: Volume 5 started at: Mon Jan  6 23:23:32 2003
	  DUMP: Volume 5 begins with blocks from inode 6452301
	  DUMP: 86.90% done, finished in 2:10
	  DUMP: 87.44% done, finished in 2:05
	  load: 0.35  cmd: dump 7998 [pause] 0.46u 1.90s 0% 656k
	  87.70% done at 73 KB/s, finished in 2:02

	which is far less than the 800+ KB/sec that it really does...


	write a large dump and fill your tape drive remotely, have dump complain
	and ask to rewrite it.  let it do this.  have the transfer rate now be

	looking at the code it seems that restarting a volume needs to reset
	tstart_volume ...