HAST - documentation unclear to me

Erik Scholtz escholtz at argonsoft.de
Wed Jan 11 09:14:18 UTC 2012


again I'm in the need of building a FreeBSD cluster (for loadbalancing 
purposes, not for failover purposes). Still GFS, GPFS or OCFS2 isn't 
ported to FreeBSD yet, so I was reading about HAST. The one point I do 
not get is the following part:

"[..] HAST works in Primary-Secondary (Master-Backup, Master-Slave) 
configuration, which means that only one of the cluster nodes can be 
active at any given time. Active node will be called Primary node. This 
is the node that will be able to handle I/O requests to HAST-managed 
devices. [...]"

IMHO this can mean two things:

1) Only the Master can be operational, the slave is in standby (and 
therefor can not be used as loadbalancing system)

2) Slave can be operational too, but on a write-access to the slave it 
will be sent to the master, that syncs it back to the slave again (which 
will cost performance but will work).

Does anyone of you have an idea which option (1 or 2) is the way HAST 
will work?

If option 1 is the behaviour of HAST:
Any recommendations howto loadbalance an apache webserver (with 
read/write operations)? Mounting the data from a NFS-Volume costs a lot 
of time (nearly 1 second slower per request) and therefor is not 
recommended in an apache highperformance-setup.

Thanks for your answers.


My blog: http://blog.elitecoderz.net

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