Thanks for the suggestions.  Everything you suggested checked out.
Speed is definitely 1000Mb/s, no errors, and hard drive speed is
plenty quick.  Also, the tape drive itself isn't iSCSI, the enclosure
is (Spectra Logic NAStape 250).  Any other suggestions?

On Jun 18, 8:07 pm, Sparqz <[EMAIL PROTECTED]> wrote:
> I must have really dark sunglasses on, because I've never seen an
> iSCSI tape drive before?
> Anyhow, I don't think your MTU (lack of jumbo frames) is the problem,
> I can easily get 50MB/s sustained transfers over a gigabit network.
> First I would confirm that the path between your linux iSCSI server
> and your tape drive is running a the full wire speed (gigabit).
> Assuming eth0 is the ethernet port you use for iSCSI traffic type
> "ethtool eth0" and make sure you see:
>         Speed: 1000Mb/s
>         Duplex: Full
> amongst the garbage that fills the screen.
> Also, you can type "ifconfig eth0" and you should see something like:
>           RX packets:62361505 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:110583510 errors:0 dropped:0 overruns:0 carrier:0
> make sure that there are no errors (or dropped packets, overruns or
> framing errors)
> I wouldn't worry too much about the TCP Checksum messages that
> wireshark shows (usually it's because another part of the system
> checks these checksums and mangles them in the process)
> Finally, can your local disk support 30MB/s ?  might be worth
> installing something like iozone or bonnie++ to make sure your disk
> can be read and written to at 30MB/s.
> Hope this helps!
> On Jun 17, 6:27 am, Michael <[EMAIL PROTECTED]> wrote:
> > Hi all,
> > I've been using open-iscsi to set up an IBM Ultrium LTO-4 tape drive.
> > I can connect and transfer files and everything, but the maximum read
> > or write speed I can get is like 16MB/s by tweaking the block size.  I
> > am on a gigabit network, which the tape drive supports.  The drive
> > specifications rate it at 30MB/s so I'm off by 50%.  Does anyone know
> > what I can do to get the speed up to scratch?  I'm pretty much a Linux/
> > network newbie so I no idea if its an open-iscsi tweak or a network
> > tweak that I could possibly do.  Also, I checked and my network card
> > only supports MTU=1500, if that matters.- Hide quoted text -
> - Show quoted text -
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