[RC5] Multiple Clients sharing

Joe Zbiciak j-zbiciak1 at ti.com
Wed Sep 23 14:37:48 EDT 1998

'Jeff Shepherd' said previously:
| I have a unix cluster with a number of machines using a common disk area.
| It is pretty obvious I can share the executable, and perhaps even the .ini
| file it reads.  But what about the buff-in and buff-out files? 

This mostly works.  Unfortunately, buffer locking over NFS doesn't seem
to work very well in the current clients, from my experience.  If
multiple clients all jump to grab a block at the same time (a likely
occurance if all of your machines are the same speed), then there's a
significant chance that they'll all grab the same block.  A similar
phenomenon can happen when clients go to flush blocks -- the same block
can be flushed multiple times, leading to needless dupes.

What I ended up doing at the time was I set up the clients to each have
their own buff-in and a combined buff-out.  I then set them all to run
offline with -runoffline.  Separately, I ran a periodic job to fetch
into each of the individual buff-in's and to flush the combined
buff-out.  It was clunky, but it worked.

Logfiles are a different issue -- sharing those simply does not work
over NFS.  (At least it didn't for me -- I had massive log-file
corruption.)  You need a separate log file for each instance of the

| However, I'm thinking I might need a directory for
| each machine so each machine has it's own buff-in and buff-out files that
| are specified via the -in and -out arguments.

You don't need a separate directory.  Separate buff-in/buff-out files is
enough.  You could name them "hostname-in" and "hostname-out", for instance.

Another possibility would be to set the clients to not store buff-in
and buff-out files at all, and set them all to use a personal proxy.
This centralizes the buffer management at one point, and you should
always have fresh blocks.



 +------ Joseph Zbiciak -----+
 | - - j-zbiciak1 at ti.com - - |  "The meaning of a value is determined 
 |-Texas Instruments, Dallas-|   by how it is used."
 | - #include <disclaim.h> - |                          -- Ousterhout

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