cluster howto ?

[Voutsinas Nikos]

daniele.sartori at libero.it wrote:
>>On Sun, 10 Nov 2002, [iso-8859-1] daniele.sartori at libero.it wrote:
>>
>>
>>>hello, howto cluster for load balancing cyrus imap server ?
>>
>>There is doc/install-murder.html, but I suspect that isn't really what you
>>want.
> 
> 
> :) yes isn't what i want. I mean it is possible to split across several
> server the same mailboxdb (shared file system? CXFS?). 
> 

Actually there are three alternatives

a)client/server distributed FS (e.g. NFS)
b)symmetric shared FS (e.g. GFS)
c)asymmetric shared FS (e.g. C-XFS, QFS4.0)

In any case you ll have problems with the provided locking mechanisms 
and memory mapped files [mmap]. Even if the FS provides the same local 
unix semantics, you will notice, serious performance degrade due to the 
  email-imap-cyrus I/O profile witch is random, write-heavy with small 
avg file sizes.

Despite the rumors, and if you are insist on trying a shared FS (like 
me), get ready for a SSD (Solid State Disk) solution for the Metadata 
server.

BTW:CMU guys, have you ever thought of using/testing Shared FS before 
going on Murder? (I dont mean NFS...)


Nikos Voutsinas
Network Operations Center
University Of Athens