Kern Sibbald wrote:

>> Wish 1: It would be nice to allow a Pool or Job to have a choice between
>> more than "one or all" of the available drives (that's effectively what
>> "prefer mounted volume") gives.
> 
> Yes, I can see the utility of that.
> 
>> Wish 2: (related) It would be useful to have max concurrent job limits
>> per pool.
> 
> Yes, perhaps.  Though with so many max concurrent jobs, it becomes a 
> nightmare 
> to understand what is going on.

How about making it optional and defaulting to unlimited?

>> Wish 3: It would also be good to have bacula take notice of the
>> per-drive limits on an autochanger:
> 
> I wasn't aware that this was a problem.  If it is, it is probably a bug.  The 
> main use for the drive limits is for autochangers.

It definitely is for me. I'm regularly seeing a large batch of 
long-lived low priority jobs preventing short-duration high priority 
ones from running. The only workaround seems to be to dedicate a drive 
to the high-priority ones, which is counterproductive.

>> Wish 4: It would be good to be able to define a group of clients and
>> then set maximum concurrent jobs for that group.
> 
> This is a rather ambitious project.

I know. The issue here is that while there may be 85 "clients" the 
reality is that there are 4 "real" clients and they're mostly feeding 
off one disk array (42 drives). Having that many jobs running 
simultaneously causes it to slow down badly. Setting concurrent job 
limits in the file-daemons causes excess jobs to generate error messages 
or fail, as well as preventing status gathering.

>> Wish 5:  Better optimisation/caching of directory lists (is this possible?)
> 
> Not much chance this will be done as it is an OS file system problem, not 
> Bacula's ...

It's a general scaling problem - this limit occurs in all FSes and all 
OSes to some level or another and it's something which may result in 
substantial incremental speedups.

Even UFS, Reiser and XFS fare badly when there are 100-500,000 files in 
a directory (the worst case I've seen so far had something in excess of 
2.1 million files in one directory).

Keeping directory activity down to minimums should pay dividends on 
ever-growing filesystems.




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