Re: [Bacula-users] slow despool to tape speed?
2012-04-12 20:57:50
In continuing testing here I am still unable to get full speed even when using
the 96-drive array (16x 6-drive raidz2 vdevs). Which is just insane. Also
tried a raid-0 of 16 drives as a spool array.
Now the last volume I just tried ended with this:
2012-04-12 19SD-loki JobId 2: End of Volume "FA0064" at 66:91229 on device
"LTO4" (/dev/nst0). Write of 64512 bytes got -1.
Which I find interesting as the 64512 there would (in my mind) assume that
bacula is trying to write 65K blocks? This is the exact same number of the
last block written on each volume. If bacula WAS writing this small of a
block size I could see where the problem is.
My bacula-sd.conf is:
---
Device {
Name = LTO4
Changer Device = /dev/sg87
Alert Command = "sh -c 'smartctl -H -l error %c'"
AlwaysOpen = yes;
Archive Device = /dev/nst0
AutomaticMount = yes;
Maximum Block Size = 4194304
Maximum File Size = 10G
Maximum Job Spool Size = 800G
Maximum Network Buffer Size = 262144
Maximum Spool Size = 12800G
LabelMedia = No
Media Type = LTO4
RandomAccess = no;
RemovableMedia = yes;
Spool Directory = /scratchdir/spool0
}
-------
So I'm trying to set it to 4MiB here. (Again running 5.2.6 and seeing in teh
release notes that this was uppped to 20MB max). I also tried 2097152.
Drive itself is set to variable block sizes and when loading the module it
shows it can handle up to 16MiB-1:
Apr 4 13:08:52 loki kernel: [ 72.194766] st 8:0:17:0: Attached scsi tape st0
Apr 4 13:08:52 loki kernel: [ 72.194767] st 8:0:17:0: st0: try direct i/o:
yes (alignment 4 B)
Apr 4 13:08:52 loki kernel: [ 72.350579] st0: Block limits 1 - 16777215
bytes.
So question, in the End of Volume message, is that a correct assessment that
the SD is trying to write in blocks of 64512bytes?
If so, why is it not taking the larger block size as specified in the
bacula-sd.conf file?
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