Hi Michael,

    Companies inflate their performance numbers all the time. To be fair 
the HiFN box was a full computer with a 3G Hz P4 with hyperthreading and 
1G memory. It is kind of hard to pack that into a small enclosure and 
charge little for it. It would be interesting to find out how 
Spectralogic's target is implemented but that is for another forum I 
guess...

Regards,
Charles Chou

Michael wrote:
> Charles,
>
> I was beginning to suspect this myself, having seen the www.ciao.com
> website already.  But Spectra Logic's own website lists both the
> compressed and uncompressed speeds as 32MB/s.  I'm starting to think
> they just lie on their site.
>
> On Jun 24, 8:10 pm, Charles Chou <[EMAIL PROTECTED]> wrote:
>   
>> Hi Michael,
>>
>> The spec on NAStape 250 says the transfer rate is 16MBps:
>>
>> http://www.ciao.com/Spectra_Logic_NAStape_250__10120006
>>
>> I think it is most likely the target, the enclosure in this case, that
>> is slowing things down. The native transfer rate for LTO4 is 120MBps and
>> LTO3 at 80MBps. I have tested LTO3 drive with HiFN's Sypher iSCSI box
>> and got 56MBps with 256K writes. This is with encryption on. Passthrough
>> speed was even faster. I was using open-iscsi and dt so I don't think
>> open-iscsi is at fault for the low performance you experienced.
>>
>> Regards,
>> Charles Chou
>>
>>
>>
>> Michael wrote:
>>     
>>> 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 -- Hide quoted text -
>>>>         
>> - Show quoted text -
>>     
> >
>
>
>   

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