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Re: Is my tape drive "shoe shinning" ?
2006-03-15 14:37:44
On Wed, 15 Mar 2006 at 11:48am, Guy Dallaire wrote
According to my vendor, the LTO2 drive I'm about to buy is capable of
80Gb/Hour, that is approx 50 Mb/Sec if I'm right.
Be careful with your units there. b != B. According to the data sheet I
have, native rate for LTO2 is 86.4 GB/hr, which is 24 MB/s. I've also
seen stats quoting 108 GB/hr, which is 30 MB/s.
I'm currently using an adaptec AHA2940U adapter with my DLT4000 drive.
I think it's only capable of 20 Mb / Sec...
More to the point, it's a narrow, SE SCSI adapter. It looks like most
LTO2 drives are U160 LVD.
I have a couple of question:
What adapter should I buy to feed the LTO2 drive ? It need to be
compatible with centos 4.2 (RHEL 4 clone)
I'd buy a U320 LVD card, just to be a bit future-proof. I've got my LTO3
library hooked up to a centos-4 system with an LSI 21320-R
<http://www.lsilogic.com/products/scsi_hbas/lsi21320_r.html>,
but, from the looks of it, the LSI U320 would work just fine as well
<http://www.lsilogic.com/products/scsi_hbas/lsiu320.html>.
Those use the mptscsih driver and work very well.
Wouldn't the dumpers compete for I/O's on the holding disk with the
taper process ? Or does the taper process begins writting to tape only
when all the dumpers have finished ?
Yes, they will compete. taper writes whenever it has complete images to
write -- parallelism is one of the benefits of the holding disk. That's
why, with faster tape drives, a holding RAID becomes necessary.
Where sould I look to see if my tape drive is fed properly ?
The amanda reports will tell you what speed you're writing to tape at.
Also, as noted, bonnie++ can test your disk (as can tiobench, which will
test multiple threads).
--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University
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