Hi!
I saw some related information (source:Quantum) under
http://www.datastor.co.nz/Datastor/Promotions.nsf/4a91ca5e06d20e15cc256ebe0002290e/d954d1c5e5e6df09cc25723b00740956/$FILE/When%20to%20Choose%20LTO3%20Tape%20Drives.pdf
best
Juraj
> -----Ursprüngliche Nachricht-----
> Von: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] Im
> Auftrag von Henrik Wahlstedt
> Gesendet: Donnerstag, 21. Dezember 2006 15:43
> An: ADSM-L AT VM.MARIST DOT EDU
> Betreff: Re: Performance with move data and LTO3
>
> Nice one! I get back on this after the Holidays.
>
> Thanks
> Henrik
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]
> On Behalf Of Prather, Wanda
> Sent: den 19 december 2006 18:15
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: Performance with move data and LTO3
>
> Interesting.
>
> Differences in IBM vs. HP LTO3 drives:
>
> I have been told that the IBM drives do "smart"
> compression using a bypass buffer. If a block of data is
> going to expand during compression, the IBM drives will stop
> compression and write the uncompressed block, which should
> make them a bit faster.
>
> Re tape to tape operations:
>
> I have observed the same behavior; tape to tape operations
> are inexplicably slower than you would expect when the TSM
> server is on WINDOWS. I have observed this with fibre
> drives, and SCSI drives, 3590 and LTO. I suspect it has
> something to do with buffer use, but since Windows provides
> no tools whatever to measure performance of tape devices or
> buses with tapes on them, I've never been able to make any
> other determination.
>
> I don't think it is a READ issue with the drives. Try
> testing using an AUDIT; that just reads the tape and doesn't
> write anything. I suspect you'll get faster READ times. I
> would be interested in seeing your results!
>
>
>
> Wanda Prather
> "I/O, I/O, It's all about I/O" -(me)
>
>
>
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]
> On Behalf Of Henrik Wahlstedt
> Sent: Thursday, December 14, 2006 10:37 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Performance with move data and LTO3
>
> Hi,
>
> I wonder what transfer rates (move data from drive to drive)
> I am supposed to see with LTO3.
>
> I have two TSM servers, one 32-bit Win2k3 and one 64-bit
> 2.6.9-11.Elsmp, with a SL500 and FC LTO3 drives.
> Similar HW (HP DL585) except for one server have HP- and the
> other have IBM drives. Drives are on separate PCI busses.
>
> I used a dataset of 50Gb with large files, same file type on
> both systems. Only scratch tapes and no expiration on the datasets.
> No other tape activity on the systems during the tests.
>
> I tested disk->mt0->mt1->mt2->mt3->mt1->mt0->disk
> From disk to tape I get a throughput of 74-76Mb/s with IBM
> drives, (migration).
> From tape to tape, (move data), with HP drives I get a
> throughput of 30-46Mb/s and with IBM drives I get 39-59Mb/s.
> From disk to tape, (move data), with IBM drives I get a
> throughput of 44Mb/s.
>
> Apperently write speed seems OK but read spead is an issue?!
> Or is this normal?
>
>
>
> Thanks
> Henrik
>
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