* Jon LaBadie <jon AT jgcomp DOT com> [20070802 13:23]:
> On Thu, Aug 02, 2007 at 12:03:35PM -0400, Jean-Francois Malouin wrote:
> > 
> > My bad, replying to myself...
> > Here's the outpout of 2 simultaneous running dd's on non-compressing
> > tape devices daisy-chained to the same scsi hba (LSI U320 PCI-X):
> > 
> > grumpy:~# time dd if=/dev/zero of=/dev/nst0 bs=32k
> > dd: writing `/dev/nst0': No space left on device
> > 12424636+0 records in
> > 12424635+0 records out
> > 407130439680 bytes (407 GB) copied, 7003.39 seconds, 58.1 MB/s
> > 
> > real    116m43.419s
> > user    0m11.317s
> > sys     3m7.260s
> > 
> > grumpy:~# time dd if=/dev/zero of=/dev/nst1 bs=32k
> > dd: writing `/dev/nst1': No space left on device
> > 12424636+0 records in
> > 12424635+0 records out
> > 407130439680 bytes (407 GB) copied, 7002.45 seconds, 58.1 MB/s
> > 
> > real    116m42.477s
> > user    0m11.677s
> > sys     3m6.480s
> > 
> > Looks good to me.
> > Not sure why amtapetype tops at 40MBs. 
> > 
> 
> Size is less than amtapetype:  Earlier you said amtapetype
> gave ~386GB.  dd's decimal 407 gig is 379GB binary.

Of course you're right!
And I made the same mistake twice: actually the tapetype length was
386048 mbytes which is in fact 377GB binary *not* 386GB decimal as I
posted on the first post of this thread.


> 
> As to speed, dd is only using the scsi controller for
> writing, does amtapetype use it to also read its data?

Not sure how it works. I guess I'll have to get dirty
and look at the source...

jf

> 
> jl
> -- 
> Jon H. LaBadie                  jon AT jgcomp DOT com
>  JG Computing
>  4455 Province Line Road        (609) 252-0159
>  Princeton, NJ  08540-4322      (609) 683-7220 (fax)

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