[Linux-cluster] Need some advice, setting up first clustered FS

[James Dyer]

I'm trying to set up my first clustered FS, but before I waste time trying 
things, only to find they don't work, I thought it would be a good idea to 
ask the esteemed members of this list for some opinions.

At the moment, I have three webservers, which share storage via an NFS 
mount to a server with 1TB space on it, The file server exports a 800GB 
partition to these servers.  The 800GB partition is a stripe over 2 
500MB SATA disks. This 800GB partition is syncronised to another server 
using Unison every 30 mins.

NFS is really not working for us; hitting all sorts of problems with it. 
Additionally, the above solution is obviously not at all fault tolerant, 
nor expandable, so it's time to look at other options.

Budget limited at the moment, so really need to stick with the hardware 
I've currently got.

The solution I'm thinking of is as follows; I'd like some opinions on 
whether or not this is a good idea, or if it's stupid, or impossible etc.

1- On each of the file servers, keep the existing 800GB raid0 stripe. 
2- Using vblade, present these stripes to both file servers over AoE
3- On each file server, create a raid1 volume of both raid0 stripes
4- Put a gfs filesystem on the raid1 volume, mount on webservers using 
   gfs etc.

Some questions:
1- I'm not sure if stage 3 is do-able or not. I'm not sure if I can create 
a raid1 volume from two AoE volumes. Some things I've read say no, some 
say perhaps.
2- Can I actually present a device over AoE to the same physical server 
it's installed in, or would the volume need to be made from the AoE 
device from the other server, and the physical device on this server? 
(think that question kinda makes sense...)

Really keen to make this very expandible in the future, and fault 
tolerant, so would expect to move to a raid5/10 system at some point. 
This would be accomplished by having more file servers exporting a stripe 
over AoE.   At this point, I would imagine I'd have a couple of servers in 
front of the disk farm servers to actually create the gfs partition, and 
it is these servers that the webservers would communicate directly with.

Hope what I've written makes some semblance of sense...

Thanks in advance for any advice/pointers

James


-- 
July 27th, 2007 - System Administrator Appreciation Day - http://www.sysadminday.com/