Hi Experts,

I'm worrying about creating independent filesets which start to get in the way 
of one another:

Let's pretend I create independent "fileset1" with a new inode space and 
preallocate say 1 million inodes.

I start pushing files in to fileset1. I also start pushing files in to the root 
fileset.

When fileset1 fills up, and because I've not specified a maximum number of 
inodes at creation time, presumably the file system manager gets on the case 
and preallocates more inodes as needed for fileset1. But while fileset1 has 
been filling up, I've also been filling up the root fileset (pretend I put 5 
million files in there by the time fileset1 filled up).

Now what happens? I'm guessing the FS manager starts chopping out sections of 
the root fileset beyond the 6 million region and marking them as independent 
and belonging to fileset1, in much the same way as it extends the allocated 
inode space when the file system starts running low. I hope this happens 
anyway. Let's say it does.

So, now what about performance when running policy engine scans? I'm wanting to 
speed things up by restricting the policy scan to fileset1 (because I know 
that's where I put my special files). So I write the rules to select files and 
give them to mmapplypolicy. Does performance go down the drain as my once 
neatly arranged inode space is fragmented by not having enough inodes 
preallocated to begin with?

Imagine fileset1 and the root fileset filling continuously at a similar rate 
and constantly "overtaking" one another in the inode space... does the 
performance advantage of independence start to go away rapidly?

Cheers,
Luke.

--

Luke Raimbach
IT Manager
Oxford e-Research Centre
7 Keble Road,
Oxford,
OX1 3QG

+44(0)1865 610639


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