>> > I tried to do that years ago but I believe this made all tapes that
>> > were already written to unreadable (and I now have 80) so I gave this
>> > up. With my 5+ year old dual processor Opteron 248 server I get
>> > 25MB/s to 45MB/s despools (which measures the actual tape rate) for
>> > my LTO2 drives. The reason for the wide range seems to be
>> > compression.
>> 
>> Can anybody confirm or rebute this for 2.2.x? I'm currently fiddling
>> with Maximum Block Size and a shiny new tape. It looks like 1M is too
>> much for my tape drive, but 512K seems to work and it's making a huge
>> difference: btape fill reports > 60 MB/s right at the beginning, then
>> drops to abour 52 MB/s.
> 
> With
> 
> Maximum File Size = 5G
> Maximum Block Size = 262144
> Maximum Network Buffer Size = 262144
> 
> I get up to 150M MB/s while despooling to LTO-4 drives. Maximum File
> Size gave me some extra MB/s, I think it's as important as the Maximum
> Block Size.
> 

thanks for providing this hints. just searching why my lto-4 is writing 
just at 40mb/s. will try them out!

searching the "Maximum File Size" in the manual I found this:

If you are configuring an LTO-3 or LTO-4 tape, you probably will want to 
set the Maximum File Size to 2GB to avoid making the drive stop to write 
an EOF mark. 

maybe this is the reason for the "extra mb/s". 


- Thomas


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