SANs enable disk storage to be shared amongst different server clients but each server only sees its own part of the SAN. The files or database records on the SAN are not shared between server clients. (That's typically done through a NAS.) The Red Hat purchase of Sistina gives Red Hat ownership of a product to provide file sharing off a SAN using a clustered or global file system (GFS).

Now a second Linux clustered file system supplier has piped up, PolyServe, and it says it's far more important to enterprises than Sistina. PolyServe president and CEO Mike Stankey says, "The fact of the matter is," in the classic opening statement of a put down, "that Sistina's few global file system customers have been limited almost exclusively to scientific or numerical computing applications." To complete the putdown Stankey points out that in these cases, "The rigours of commercial workloads are non-existent."

Clearly Red Hat bought the second best company. Happy Christmas.

To hammer home the point PolyServe says it has over 300 mission-critical customers and "two of the largest Linux database proof points".* What's more Sistina will need two years work for its products to become suitable for the mission-critical enterprise market as PolyServe's Matrix Server already is.

Matrix Server is a symmetrical implementation with no master server controlling access to the shared files for the other servers. This, it says, means that, unlike Sistina, it has no single point of failure. The trouble for PolyServe is that the leading world-wide Linux distributor has just bought its competitor. So the prospect exists of Red Hat bundling Sistina products into its Linux distribution making the PolyServe alternative an additional purchase (of a support licence). Ouch.

Shades of Microsoft here with its movable operating systems boundary, one that has expanded outwards to include the browser and the media player and other items, causing much discomfort to competitors, employment to lawyers, inconvenience and restricted choice to customers.

However, the Linux situation is much better. PolyServe can always go talk to SuSE, now with a contact down the road from PolyServe's Beaverton, Oregon, office in Novell, Utah.

* 'Proof point' is marketing-speak for customer.