I'm sorry to interject without having read the complete thread but I wanted to share (remind of previous emails) that I had a problem with my LTO on Solaris a while back. Turned out the HBA card was failing, the A side was dropping in performance with no additional/errors noticable which the B side of the card remained OK.
Be sure to eliminate the HW if you haven't already. On Wed, Mar 07, 2007 at 01:29:56PM -0500, Joshua Baker-LePain wrote: > On Wed, 7 Mar 2007 at 11:45am, Kenneth Berry wrote > > >The computer mbthome is both the amanda server and client, it is a Dell > >PE2650 dual Xeon processor, 2GB Ram. Tape unit is LTO3 on a dedicated > >SCSI controller. Internal HDD's are four SCSI ultra320 10K configured > >as hardware RAID5. On top of this 100GB RAID5 disk is LVM Volume00 > >allocated as shown below. One additional internal SCSI ultra320 10K > >drive of 300GB capacity is allocated to LVM Volume02 and usage can be > >seen below. All the internal HDD share a common percraid controller. I > >have an external RAID5 set of drives on an third SCSI controller which > >LVM Volume01 resides. It should not be a factor currently it is unused. > >Over the past weekend I migrated all the /home data from the external > >set of drives to the single large internal drive, thinking the external > >drives were the problem. But this reorganization made not difference. > > Some quick things to look into: > > 1) Benchmark your various volumes with both bonnie++ (single thread > streaming) and tiobench (multithreaded). This will give you some baseline > numbers. You can also play with multiple instances of dd. I have no idea > how good those perc controllers are, as Dull tends to obfuscate them > compared to their LSI underpinnings. > > 2) LTO3 is *fast*. Reading from a 4 disk RAID5 should be able to keep it > streaming, but simultaneously writing to that same RAID5 is likely to be > *very* slow... Actually, looking at your tape write speeds in the > original mail, they're barely where they should be. LTO3 can throttle to > 1/2 its native speed of 80MB/s before it has to resort to > drive/tape-lifetime-degrading stutter-stop-restart behavior. One thing > that significantly helps is increasing your blocksize from amanda's > standard 32KB -- I use 2MB. This requires recompiling amanda. > > >/dev/sdd1 141003764 36925740 96915448 28% /amanda > > Erm, where does sdd fit in in terms of the LVM volumes? > > Also, both of Jon's suggestions (spindle numbers and filesystem profile on > /home) are good ones to look into. Again, you can do your own > benchmarking outside of amanda to get a more controlled look at what's > going on. > > -- > Joshua Baker-LePain > Department of Biomedical Engineering > Duke University --- Brian R Cuttler [EMAIL PROTECTED] Computer Systems Support (v) 518 486-1697 Wadsworth Center (f) 518 473-6384 NYS Department of Health Help Desk 518 473-0773