LTO-3: optimizing blocksize
2007-08-01 11:39:23
Hi,
This is not strickly an question pertaining to the list but I'm sure
some of you have faced this issue: I just got a new ArcVault24
librarie with 2x LTO-3 tape drives and searching through the amanda
archives I found posts that claim that the default amanda 32k tape
blocksize is not really optimum for that sort of drive if I want to
avoid shoe-shining.
Hardware:
I've setup the default access device to the drives as non-compressing.
The library is hooked through a LSI U320 PCI-X scsi card to a 4
DualCore2 Xeon with 8GB of RAM running Debian/Etch running a 64bit
kernel 2.6.21.5-i686-64-smp. It should be beefy enough :)
Running amtapetype with different blocksize gives me ~386MB for
capacity (close enough to 400MB) but I never seem to get close to
streaming:
bs= speed=
32k 50482 kps
128k 50531 kps
256k 50508 kps
512k 50521 kps
1024k 50512 kps
2048k 15780 kps
4096k 15875 kps
Any hint on what I should try next?
And finally: is there a utility on Debian or Linux in general that
would allow me to see the IO transfer rate to character devices. I
know how to do this on Irix but dunno if it exists in the Linux
universe.
(gratis irix trick: start osview and look for 'phread' and 'phwrite'
in the menu 'Other'. They give the aggregated physical IO transfer
rate to all character devices)
thanks jf
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<° ><
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