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

Apple has announced the general availability of the Xsan 1.0.1 update. The 1.0.1 Update delivers overall improved reliability for Xsan and requires the use of Mac OS X or Mac OS X Server version 10.3.9. It includes improvements for:

• using the mv command to move files from Xsan (ACFS) to Mac OS Extended (HFS+) volumes
• saving files over 4GB via SMB/CIFS to an Xsan volume hosted on Mac OS X Server
• greater server stability when resharing Xsan volumes via NFS
• eliminating spontaneous metadata controller failovers that can result in slow file performance

To download this Update, please visit the website: http://www.apple.com/support/downloads/xsanupdate101.html.

For detailed information on this Update, please visit this website: http://www.info.apple.com/kbnum/n301211.

Over at AFP548.com, maccanada has posted a well-written article for how to spec out a small Xsan, with three SD and one HD edit stations.

Thomas Wolf describes why Avid and Xsan can't work together, and then explains how his company came up with a solution.

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: