Distributed File System Choices: Red Hat Storage, GFS2, & pNFS

Red Hat has several options for storage needs — GFS2, CIFS, (p)NFS, Gluster.  It’s all about right tool for the job.

http://www.redhat.com/summit/sessions/index.html#103

RHEL Resilient Storage – GFS2

Shared storage, scales up to 100TB per instance, supports 2-16 nodes in the cluster, x86_64 only.

Performance is directly related to server and storage class, and to access sets — best case is where each node generally access its own filesystem area, worst case is where nodes are fighting for locks of the same files/directories.

RHEL NFS Client

It’s an NFS client — what else needs to be said?

pNFS

Metadata server tells you where to go to get your data, and can even reference data across multiple-tiers — NFS or directly to the SAN.

Performance can be enhanced with large write caches, internally tiered storage, and is suitable for most workloads, even transactional DBs (using O_DIRECT).  Not so good for highly random read workloads.

Red Hat Storage (Gluster + utilities, support, and blueprint)

RHS is a standalone product.  RHS servers in supported config are RAID6+local storage, XFS filesystems, dedicated RHEL6.x and Gluster software, all deployed on commodity hardware (reducing cost).

Clients use Gluster for scalability; NFS or CIFS for simplicity.

Performance improved by scaling horizontally across servers.  But, there is no write cache, and Gluster is a user=space filesystem with some overhead from context switching.  Likely not suitable for big I/O (databases, mail servers), but great for big unstructured data.

Scales to 6PB (or 3PB mirrored), and can add capacity dynamically.

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