Yes you're right, once you've written on any LTO tape using an LTO3
drive, you cant read it from an LTO2 or LTO1 drive.
 
I have some LTO3 drives with master server on HP-UX, I have found that
you should read from at least 3 filesystems at the same time (MPX = 3)
and these filesystems in my environment have storage connected by a 2Gb
fibre to an entreprise storage array. I get ~35 MB/s write on the drive.
 
If you have a windows server, or you're not connected to a large stoage
array, you probably wont be able to pump out enough data to handle a
direct stream write on the drive. I recommend you stage the data on a
local disk first and then destage to disk, this will speed up the read
performance as you are reading from local disk and one/few large files.
 
 
Wessam Aly 
Senior UNIX & Storage Systems Admin. 
HPUX-CSA Certified Systems Administrator 


________________________________

From: Weber, Philip [mailto:Philip.Weber at egg.com] 
Sent: Tuesday, 19 December, 2006 19:30
To: Wessam Aly; Dave Brown
Cc: veritas-bu at mailman.eng.auburn.edu
Subject: RE: [Veritas-bu] LTO3 Read/Write LTO2


I've also heard that once you've used LTO2 media in an LTO3 drive, you
can't then read it in an LTO2 drive.  Not sure where I got this from
though.
 
I've also got some new LTO3 drives having asked for LTO2...so far they
seem to be running slower than the LTO2s as I can't supply data to them
fast enough :-(... time to play with mpx and buffer sizes...
 
Phil Weber 
Business Technology (Egg) 
Storage Technical Services - Senior UNIX Technologist 

-----Original Message-----
From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Wessam
Aly
Sent: 19 December 2006 17:04
To: Dave Brown
Cc: veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] LTO3 Read/Write LTO2


        Dave.. AFAIK, LTO3 will surely read LTO2 and LTO1 tapes no
problem. but it is not recommended to write with an LTO3 drive on an
LTO2 tape. The densities do make a difference in operation.
         
        Some manufacturers also do not officially support it, but either
way, technically you should be able to read/write LTO2 tape with an LTO3
drive, but you'll be limited to the normal LTO2 capacity.
         
        Regards,
         
        Wessam Aly 
        Senior UNIX & Storage Systems Admin. 
        HPUX-CSA Certified Systems Administrator 
        
         
        
        
________________________________

        From: Dave Brown [mailto:dbrown at worknetinc.com] 
        Sent: Tuesday, 19 December, 2006 16:29
        To: veritas-bu at mailman.eng.auburn.edu
        Subject: [Veritas-bu] LTO3 Read/Write LTO2
        
        
        Well,  My boss just got me a new LTO3 drive to put in my
library.  I asked for an LTO2 as I already have 2 of these in the lib
and 100's of tapes but I have one nonetheless
        
        The lib sees the drive as does NetBackup but it says that there
are no tapes available...barcode reader I'm sure.  
        
        Is there a way to make the LTO3 use the LTO2 tapes and write to
them at the proper density ?
        
        I tried changing the type to hcart2 as my others are but it did
not take.  I may have to restart services but have to wait for some jobs
to finish.  Figured I'd throw it up to the group while I wait.
        
        NetBackup 6.0 MP4
        Windows 2003
        Quantum 1500 lib
         
         
         

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