Re: [Bacula-users] mbuffer as tool for concurrent spool/despool

Hello,

2012/12/7 Stieneke, Dan <Dan.Stieneke AT ars.usda DOT gov>

Reading the mail archive, it seems I’m not alone in wanting to see concurrent spooling/despooling.

Could we hand off the job to a standalone spooler like mbuffer (http://www.maier-komor.de/mbuffer.html)? For a simple tar to LTO-4 job it makes a tremendous improvement.

The main problem with concurrent spooling/despolling in Bacula Storage Daemon is not a buffer/fifo (which is already implemented because we have a spooling functionality already) but single job thread. It is not easy to implement concurrency with a current code. In this case mbuffer does not simplify things.

The Bacuala developers would need to modify the storage daemon to allow the datastream to be diverted out and then back in through a pair of FIFOs before it gets [properly re-blocked? and] written to tape.

Simply speaking developers have to implement a multiple threads for single job which write data to tape. This is a main missing code for build in concurrent spooling/despooling. :)

The user would need to tie the FIFOs together with an external spooler. It might look like this:

------/etc/bacula-sd.conf------

<snip>

Device {

…

PushToFIFOSpooler = /path/to/bufreceive # bufreceive is a FIFO on this machine

First thread to read data from client and write data to the buffer - implemented already.

PullFromFIFOSpooler = /path/to/bufsend # bufsend is also a FIFO

Second thread to read data from buffer and write to bacula device - missing.

best regards

--
Radosław Korzeniewski
radoslaw AT korzeniewski DOT net

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