Yes, correct that it's rated at that max speed. But if you don't have a pipe
big enough to handle the max speed, the other question is how small can the
pipe be before it becomes problematic and unusable. I just checked, and
according to Fuji, an IBM LTO4 drive will speed match down to 30MB/sec, which
means you will still be able to get some useful work done with a smaller pipe.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDIQFjAA&url=http%3A%2F%2Fwww.fujifilmusa.com%2Fshared%2Fbin%2FLTO_Overview.pdf&ei=i6IaUYuHGqn-0gHlmIGwDQ&usg=AFQjCNFcZqFcjcsiAWUCkWiXcmVwqbUgJQ&bvm=bv.42261806,d.dmQ&cad=rja
..Paul
At 02:38 PM 2/12/2013, Shawn DREW wrote:
>LTO4 is rated at 120MB/s max speed, which comes out to just under 1gbit/sec
>(1gbit/s = 125MB/s). I normally reserve 1gbit for each LTO4 drive. (i.e. 4
>drives on a 4gb HBA)
>I do see 110+MB/s streaming on those guys. (using topas -T on AIX, so not
>sure about the accuracy)
>
>
>Regards,
>Shawn
>________________________________
>Shawn Drew
>> -----Original Message-----
>> From: ADSM-L AT VM.MARIST DOT EDU [mailto:ADSM-L AT VM.MARIST DOT EDU]
>> Sent: Tuesday, February 12, 2013 12:04 PM
>> To: ADSM-L AT VM.MARIST DOT EDU
>> Subject: Re: [ADSM-L] 1 GBit FC sufficient for tape library?
>>
>> Another thought: You really want to avoid the LTO4 drives dropping out of
>> streaming mode, even if 1Gb/s is enough bandwidth to theoretically move
>> the amount of data you need to move. I believe LTO4 will operate down to
>> 30-40MB/s. Worth checking, since I'm not sure, but I'm pretty sure you can
>> drop as low as 40MB/s and still stay in streaming mode. Once you drop out of
>> streaming mode, your throughput will go in the dumper, and you won't get
>> anything close to 1Gb/s throughput.
>>
>> At 10:15 AM 2/12/2013, Michael Roesch wrote:
>> >Hi Stefan,
>> >
>> >one quick question: what are the numbers you are using for your
>> >calculation?
>> >
>> >Did you convert 240 MB/s into Gigabit/s?
>> >
>> >Thanks
>> >
>> >Regards,
>> >Michael
>> >
>> >
>> >
>> >On Tue, Feb 12, 2013 at 1:01 PM, Stefan Folkerts
>> ><stefan.folkerts AT gmail DOT com>wrote:
>> >
>> >> Yes, two LTO4 drives would not be happy at all behind a 1Gb/s HBA,
>> >> even two 1Gb/s HBA's are not enough to fully utilize the drives.
>> >> I would imagine you could also run into driver/firmware issues with
>> >> this combination since it's a very strange one but then again....it
>> >> would probably work just slow.
>> >>
>> >>
>> >> On Tue, Feb 12, 2013 at 12:34 PM, Michael Roesch
>> >> <michael.roesch AT gmail DOT com>wrote:
>> >>
>> >> > Hi Stefan,
>> >> >
>> >> > the drives are LTO4 ones. So the HBA would be the bottleneck
>> >> >
>> >> >
>> >> > On Tue, Feb 12, 2013 at 11:36 AM, Stefan Folkerts <
>> >> > stefan.folkerts AT gmail DOT com
>> >> > > wrote:
>> >> >
>> >> > > If it is LTO1 or LTO2 you would be OK, if it is LTO3 or higher
>> >> > > you are limiting your drivers with your HBA.
>> >> > >
>> >> > >
>> >> > > On Tue, Feb 12, 2013 at 10:39 AM, Michael Roesch
>> >> > > <michael.roesch AT gmail DOT com>wrote:
>> >> > >
>> >> > > > Hi all,
>> >> > > >
>> >> > > > we have an old HP MSL 6030 with two drives that share one 1
>> >> > > > GBit FC
>> >> > port.
>> >> > > > Would that be enough to use with TSM? I have a feeling that says
>> "no"
>> >> > > but I
>> >> > > > couldn't find any minimum FC requirements.
>> >> > > > Anyone having more info? Maybe even an IBM technote?
>> >> > > >
>> >> > > > Thanks
>> >> > > >
>> >> > > > Regards,
>> >> > > > Michael Roesch
>> >> > > >
>> >> > >
>> >> >
>> >>
>>
>>
>> --
>> Paul Zarnowski Ph: 607-255-4757
>> CIT Infrastructure / Storage Services Fx: 607-255-8521
>> 719 Rhodes Hall, Ithaca, NY 14853-3801 Em: psz1 AT cornell DOT edu
>
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Paul Zarnowski Ph: 607-255-4757
CIT Infrastructure / Storage Services Fx: 607-255-8521
719 Rhodes Hall, Ithaca, NY 14853-3801 Em: psz1 AT cornell DOT edu
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