[OpenAFS] openafs fileservers in VMware ESX

[Derek Atkins]

I've never seen any reason to virtualize an AFS server.  Ever.  The key is IO
bandwith, which isn't increased by virtualization.  You really want separate
PHYSICAL servers for AFS servers.  Virtualization does not give you any
benefits due to hardware failure, power failure, or any other failure.  It just
adds overhead.

-derek

Quoting Matthew Cocker <matt@cs.auckland.ac.nz>:

> Hi
> 
> We have just invested in a Fibre Channel SANs and several FC attached 
> ESX servers (brillant product, just love vmotion and virtual center) and 
> are playing with Virtualised Openafs Fileservers. All is working very 
> well except if we put to many volumes on a server at which point "vos 
> listvol" takes a very long time to return.
> 
> If we have say 5000-7000 volumes (about 50Gb) on a vice partition 
> performance is equivalent to hardware server. At 10k volumes to 40k 
> volumes 100-300Gb we have problems with vos listvol.
> 
> This is not a huge problem for us as we wanted to do more smaller 
> machines any way to take advantage of the VM environment but it does 
> make me wonder why this occurs.
> 
> What exactly does vos listvol do? does it scan the vice partitions and 
> return all the volumes it finds (du -sh /vicepa takes a huge amount of 
> time too so maybe this is a vm issue)? Is any network traffic exchanged 
> with the DBs?
> 
> When we start vos listvol on the virtualised server with lots of volumes 
> it just seems to stop working with the cpu usage for the afs process not 
> jumping above 1-2%. An strace (available if anyone interested) shows the 
> vos listvol is doing something (although very slowly).
> 
> If the virtualised server has less volumes cpu usage jumps up to 30-50% 
> and every thing works.
> 
> The only thing effected seems to be vos listvol as accessing a volume 
> stored on the server is quick (from user point of view). vos backup 
> stuff all seems to work.
> 
> Hardware server with same number of volumes works OK.
> 
> SANS monitoring suggests there is not a data access issue on that side.
> 
> Not sure this is an AFS issue but any suggestion to help me understand 
> why vos listvol is effected so badly apprepriated.
> 
> Cheers
> 
> Matt
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> 


-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord@MIT.EDU                        PGP key available