[BNM] fs mirroring on Linux

[Quentin North (noisy)]

Al James was interested in replicated (as distinct from mirroring)  
filesystems on Linux between servers.

NFS will allow remote mounts, but in itself doesnt replicate  
anything. This will work with fopen, as it is in the kernel and  
transparent to application. You could mount the fs locally on the  
primary machine, export it as NFS, and then mount it as NFS on the  
secondary (remote) server. You would need to tune extensively over a  
WAN.

rsync will replicate files, it depends if you need synchronous  
replication or how long you can accept a lag. You just set this up as  
a cron job.

A similar approach to rsync, using ftp, can be achieved using  
mirror.pl. Likewise a cron job if you can accept a lag and  
asynchronous replication.

GFS is probably the best way to go. It is essentially a clustered  
filesystem, and as such is synchronous. However, it is only available  
with RHEL Enterprise Advanced server and is complicated to set up.  
This is a expensive subscription. GFS is not open source (although an  
early version was, it has been significantly enhanced by RH as a  
premium product). You wont find it in CentOs.


Quentin