Re: SCSI interface cards.

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Hi Roger / All  --

ls -la
-rw-r--r-- 1 root root 8130652160 2008-04-08 11:07 sys.dump

dd if=sys.dump of=/dev/null
15880180+0 records in
15880180+0 records out
8130652160 bytes (8.1 GB) copied, 28.5627 s, 285 MB/s

I did the test you recommend and got the above. I think I could come
close to flooding that interface. I was looking at the:

http://www.newegg.com/Product/Product.aspx?Item=N82E16816103066

$200.00 (1) Adaptec 2250300-R PCIe x 1 SCSI 29320LPE Kit - new scsi
card to increase  bandwidth on lto4 tape system.
(my current card is U160/133 pci-x, but i have a PCIe x 1 free)

I haven't found any major problems searching the web on this card. Do
you have a recommendation on a LSI card?

Thanks much for all you input, I'm mostly a lurker of the list, but
I've learned mucho and keep reading and learing!

-- Gary

>  > Hi Roger --
>  >
>  > Thanks for the quick responses. The backup unit is a Overland arcvault
>  > 12 w/lto4 drive. The lto4 have,
>  > I think, 120MBps (Native)/240MBps (compressed), so no gain using U320
>  > interface? I'd guess the max thru put
>  > would be 120MBs, with the compressed rate just accomplished because of
>  > data compressing. Sorry to
>  > be thinking out loud here, but this does help!
>  >
>  >
>  > -- G
>  >
>
>  Well, if that is what you have, you did spend some decent money on it.
>
>  The important part it LTO4.   Native speed is 432GB/hr, or 120MB/second, if you
>  get good compression and you have a *FAST* disk subsystem, then you could use
>  that speed, I would test doing a backup with you backup software to /dev/null
>  and see what the actual disk speed is, if you are backing up a lot of small
>  files you won't be able to use all of the speed, or if the files are fragmented
>  on disk you may not be able to use that speed.
>
>  If you data does not compress good you won't be able to go over 160 MB/second
>  either.
>
>  You would have to be getting the data locally from a high-end disk subsystem,
>  and you have to have big files, and you would have to data that was
>  compressible.    Overall you have to be pretty careful to get something that
>  will read at 120MB/second and also write out to a tape at 120MB/second, you have
>  to make sure the PCI-X slots are not shared with each other, and that all other
>  subsystems can do it.
>
>  And if your current SCSI card is PCI (not-X, not-64bit) then the actual limit
>  is probably < 132MB/sec (PCI limit).
>
>  I would try what you have and see what speed you are getting, if you run within
>  20-30 of the limit you may be hitting the limit, if you are much below that you
>  have other issues.
>
>  Generally though I have had good luck with the LSI cards, I have used their
>  SCSI, SAS, and fiber channel cards of various sorts.    If I was getting one of
>  those new I would have got either a SAS or a Fiber channel interface for it (if
>  it was available), as they tend to be less trouble than SCSI.
>
>                                     Roger
>
>
>
>
>
>  ------------------------------
>

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