=> On Thu, 30 Aug 2001 15:56:48 -0400, Lindsay Morris <lmorris AT servergraph 
DOT com> said:

> Jeff, clever! run iostat, then watch sessions start and land on different
> physical disks, on by one.
> Like the idea.

Note; the sessions do not grab and keep individual volumes;  They appear to
walk down the list of volumes, one file at a time.  This is easiest to see if
you can arrange to back up a big dir full of ~500M files. (CDROM ISOs or such)
you can watch disk activity walk down the list of disks.


> But what happens when you run out of volumes? Say you have 8 disk volumes,
> and 9 sessions.  Does the ninth session just hang, until one of the first 8
> finishes?  Or does the ninth session grab some busy volume, sharing it with
> another session?

Going out on a limb, speaking from the perspectiove of a client service
thread:

I've got a new file to write.
I get in line for a volume.
I walk up the queue.
I get priority on a volume
I write my file.
I wait for my remote client to be ready to give me another file.

So, the volumes are instantaneously locked at the file granularity.

Of course, I'm just making this up, so don't bank on it.  But it matches the
behavior I've seen so far.

Allen S. Rout