gary artim wrote:
> You guys/gals are great, very responsive! I did try
> spooling/despooling and my run times shot up.

They will - you're copying everything twice (disk to disk to tape), but 
this is the only way to achieve fast despooling speeds - if you don't do 
this then your LTO drive will start to "shoe shine" and speeds drop off 
rapidly when it happens.

The trick is to run multiple jobs at once - you have to spool to achieve 
this anyway or extracting will be a nightmare.

Spooling is a net gain when you're running incrementals.

Spooling MUST happen on a fast dedicated drive. You're best off dropping 
in a fast SSD such as a 64/128Gb OCZ vertex3 or similar to handle it.

> I was using a simple
> 7200 drive though, no ssd or raid...I assume the performance gain
> happens when your networks multi machines...wearing multiple hats so
> will report back on btape next week, unless I get some time. gary

Even on a single host, if the heads are thrashing then spooling will 
save time overall. The big advantage is being able to run multiple jobs 
so that several are spooling data at the same time one is despooling.

> On Thu, Dec 1, 2011 at 8:00 AM, Alan Brown <ajb2 AT mssl.ucl.ac DOT uk> wrote:
>> gary artim wrote:
>>> thank much! will try testing with btape.
>> Please let us know the results
>>
>>> btw, I ran with 20GB maximum
>>> file size/2MB max block (see bacula-sd.conf below) and got these
>>> results, 20MB/s increase, ran 20 minutes faster, got 50MBs --
>> You should be seeing 120Mb/s or thereabouts.
>>
>> If you're spooling/despooling then you'll see lower overall speeds of
>> course. What counts is the despooling speed.
>>
>> How much ram have you got and what are you using to connect the LTO4 drives
>> up?
>>
>>
>>
>>
>>
> 




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