Re: [Bacula-users] tuning lto-4

Subject:

From:

Radosław Korzeniewski <radoslaw AT korzeniewski DOT net>

To:

Marcello Romani <mromani AT ottotecnica DOT com>

Date:

Tue, 20 Dec 2011 11:35:45 +0100

Hello,

W dniu 20 grudnia 2011 10:30 użytkownik Marcello Romani <mromani AT ottotecnica DOT com> napisał:

>> A "direct" backup from FD into a SD tape device is performed with a little
>> buffering and require more computation, disk seeks and context switching. It
>> is a single, complicated chain with two threads one for FD and one for SD
>> connected through logical network layer (even when a full backup is
>> performed on local machine). With this chain it is very hard to get a full
>> LTO speed. As opposite when you perform SD data spooling, you can easy
>> achieve a full LTO speed because a writing chain (despooling) in SD is very
>> simple and effective. Unfortunately doing a data spool takes a long time and
>> slow down an overall backup speed.

Would be curious to know if data spooling made any difference...
Cheers!

In my reference system I've got an average backup speed of 30-40MB/s when I run a backup job with a FD->SD->LTO chain (without spooling) on local machine (full backup of a few very large files). And I've got an 80MB/s despooling speed on the same machine and LTO.

best regards

--
Radosław Korzeniewski
radoslaw AT korzeniewski DOT net

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