As anyone who has contemplated setting up an Xsan environ knows, the fibre fabric is the nervous system of the SAN. Fabric refers to all your fibre switches, cabling and HBAs (host bus adapters, the fibre channel cards in your workstations). QLogic fibre switches are Apple's recommended solution, and the manufacturer seems excited to jump into the Apple world. One feature of these switches is zoning ...

We're happy to announce an update to our home-grown Xsan defragmentation app, Xsanity Defrag.

Xsanity Defrag 1.0.1 has been updated for Xsan 1.0.1. The app is a GUI wrapped around the snfsdefrag command-line utility that ships with Xsan, allowing you to defragment files on Xsan volumes or storage pools with ease. It indicates the level of fragmentation on your Xsan volumes or storage pools, and allows you to monitor the progress of the defragmentation process.

We'll be providing support for the app in a dedicated forum on this site. All feedback is welcomed!

Question: I have a simple Xsan: two-seats, one Xserve RAID, one storage pool. After copying a whole bunch of tiny files, via the Finder, to the SAN, any write creates a file with at least 30 extents, sometimes as much as 500 on a single file. I tried defragmenting the whole volume, deleting the directories that had the zillion little files, I even upgraded the clients to OS 10.3.9/Xsan 1.0.1. The large-extent render files are not playing back unless I defrag them. My questions are: Are 30-500 extents for single files (100-500MB render files for example) normal? Do you know of anything to cure this poor file system?

Answer: We need to understand several behaviors of Xsan:

• Metadata is stored in blocks contiguous with data
• Metadata is written to disk after every new file created
• Metadata is easy to fragment, and difficult (impossible?) to defragment
• New files use the first available free space on a storage pool

We're happy to announce the release of our home-grown Xsanity Defrag 1.0. This application is a GUI wrapped around the snfsdefrag command-line tool, allowing you to defragment your Xsan volumes and storage pools.

We'll be providing support for Defrag in a special forum on this site. We welcome all suggestions!

Did you know you don't need access to a RAID to explore a fully functional Xsan Admin interface? It's really quite easy to walk through the various setup options without any significant hardware investment at all. All you need is a blank piece of storage media to label as an available LUN. A blank FireWire drive is ideal, though amazingly, an item as minimal as a USB key has narrowly sufficed. If you’re comfortable proceeding at your own peril, and if you don’t mind that your mileage may vary, here’s what to do: