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Re: [Bacula-devel] Feature request: "minimum spool size" setting

Frank> Item: Add a "minimum spool size" setting, defining a minimum
Frank> level of free space to spool new jobs

Great idea.  Lousy name.  How about "min free spool size" instead?  

Frank> Date: 20 March 2008

Frank> Origin: Frank Sweetser <fs@xxxxxxx>

Frank> What: Add a new SD directive, "minimum spool size" (or
Frank> similar).  This directive would specify a minimum level of free
Frank> space available for spooling.  If the unused spool space is
Frank> less than this level, any new spooling requests would be
Frank> blocked as if the "maximum spool size" threshold had bee
Frank> reached.  Already spooling jobs would be unaffected by this
Frank> directive.

Frank> Why: I've been bitten by this scenario a couple of times:

Frank> Assume a maximum spool size of 100M.  Two concurrent jobs, A
Frank> and B, are both running.  Due to timing quirks and previously
Frank> running jobs, job A has used 99.9M of space in the spool
Frank> directory.  While A is busy despooling to disk, B is happily
Frank> using the remaining 0.1M of spool space.  This ends up in a
Frank> spool/despool sequence every 0.1M of data.  In addition to
Frank> fragmenting the data on the volume far more than was necessary,
Frank> in larger data sets (ie, tens or hundreds of gigabytes) it can
Frank> easily produce multi-megabyte report emails!

Would it make more sense to have directives called "spool chunk size"
and "minimum free spool chunks" instead?  So you could have a chunk
size of 10mb, with a minimum free spool chunk of 2 (20mb).  

On my home machine, it's not unusual for me to end up with my entire
staging disk filled to the rim with a single staged saveset in one
large file.  

Breaking it into smaller chunks (10% of max spool size each?)  might

Dunno... I do like your idea though.


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