[Gluster-users] glusterfs alternative ? :P

[Keith Freedman]

At 05:08 AM 1/12/2009, Stas Oskin wrote:
> From Lustre wiki 
> (<http://wiki.lustre.org/index.php?title=Lustre_FAQ>http://wiki.lustre.org/index.php?title=Lustre_FAQ)
>
>
>Are fibrechannel switches necessary? How does HA shared storage work?
>
>
>
>Typically, fibrechannel switches are not necessary. Multi-port 
>shared storage for failover is normally configured to be shared 
>between two server nodes on a FC-AL. Shared SCSI and future shared 
>SATA devices will also work.
>
>Backend storage is expected to be cache-coherent between multiple 
>channels reaching the devices. Servers in an OSS failover pair are 
>normally both active in the file system, and can be configured to 
>take over partitions for each other in the case of a failure. MDS 
>failover pairs can also both be active, but only if they serve 
>multiple separate file systems.
>
>
>As far a I understand, Lustre is designed with the approach most 
>cluster file systems (except GlusterFS of course :) ), meaning you 
>have master servers that responsible for storage and retrieval of 
>the data, and storage nodes, which do actualy storage.

unless something has changed drastically since the last time I read 
up on lustre, it requires shared storage in some capacity.  Whether 
they're connected via a SCSI ring or FC-AL or iSCSI or whatever other 
mechanism, as I understand it, the machine needs to view the physical 
disks as devices on the machine, and mirrors across the block devices.

This is similar to ocfs2 which I think is superior to lustre, but 
still kind of difficult to configure.

The advantages gluster has over all the other cluster filesystems out 
there are:
1) you can use commodity hardware without having to build additional 
infrastructure (you don't need a SAN, just the same computers 
connected to the same network will do the trick)
2) replica's (ha/afr, whatever) needn't be physically connected (or 
connected by anything but a network connection.   While it might be a 
tad slow, it will work exactly the same over a wide area as within a 
data center.

While number 2 could be addressed with a remote block device (drbd) 
when used with ocfs2 or probably lustre, they require more complex 
administration.