I'm setting up a new array on an areca ARC-1260 controller - I ran out of room on my 1220! I currently have 4 Seagate 750GB HDDs in RAID 5, and will continually grow the array as needed. This is in a dedicated file & mail server running off a desktop socket 939 motherboard with an AMD 3800 X2 and 2GB of RAM. The controller is using a 128KB stripe and write-back caching is enabled. My HDDs support 300Gb/s (SATA II) and the controller supports both 300Gb/s and 300Gb/s+NCQ transfers. It's currently running 300Gb/s+NCQ.

I've decided to go with the XFS file system, as that seems to do very well with larger files and large file systems and has a lot of nice features older journaled file systems don't have. The majority of the space will be consumed with DVD files (VOBs) and eventually with HD DVD and Blu-ray files - hence the large files.

My question is: Does anyone know (or know where to go) what the ideal parameters are for the file system? I installed XFS using the default parameters and am getting about 230MB/s reads. I've seen other similar setups get nearly double that and wondering if it's something I can change in the file system parameters.

~EDIT~ I've gone through SGI's website top to bottom and can't find any specifics on the various parameters and how they may affect throughput. It's mostly just clarification and informational data.

*chirp* *chirp*

MikeSM, you out there?

I'm setting up a 3.5TB R5 array to serve videos, using a 3ware 9600 series controller, and have also been researching xfs parameters. Their website has an article (http://www.3ware.com/KB/article.aspx?id=11050)on optimizing the read ahead setting:
blockdev --setra X /dev/sda
sets read ahead to X 512 byte sectors
http://nixdoc.net/man-pages/Linux/blockdev.8.html

I've read a few pages on using bonnie++ to benchmark a file system.

The 3ware optimizations would be exclusive to 3ware because they use their own in-house developed I/O processor and proprietary algorithms. BTW, I almost got the 9650SE 16 port card, but 3ware couldn't guarantee desktop mobo compatability like areca could. Excellent cards though.

There's so many possible options in the file system structure, I don't know where to even start. Considering I've already created the file system, I don't want to hose it, but I have the capability to make online changes via xfs_admin.

Have you tried asking on the mythtv users list? Probably have a better chance of response there.

FWIW I'm using xfs for my HD recording partition too, but I just left the defaults as-is and it's plenty fast enough even with 2 records, commflag, and watching a show going. With an SATA II 500GB Samsung Spinpoint drive, that is.

Have you tried asking on the mythtv users list? Probably have a better chance of response there.
No, I didn't want to hijack it.

I'm most interested in modifying the block size and the stripe unit. Since the majority of my files will be very large, a larger block size would benefit me -- but how large? Same with the stripe.

I'll try contacting SGI and see if they're willing to offer and basic guidance.

here is the the recent xfs filesystem topic pretty much about the same thing you asked from the myth users mailing list

http://www.gossamer-threads.com/lists/mythtv/users/287953?search_string=xfs;#287953

Thanks for the link. Not really any detailed info on the mkfs/xfs_admin params though, mostly just a discussion on the presence of fragmentation or lack thereof.

I wouldn't change blocksize from default. I don't think you'll see much there. I would make sure on the controller that I used a fairly wide stripe width though, say 128k or bigger even. Though honestly, for this application, disk IO shouldn't be an issue if everything is running OK. I can record 2HD and 2SD streams simultaneously while watching another on a standard EXT LVM RAID5 array (I'm sure it could handle another SD but I've not run across a time where all 5 of my tuners were recording!). For years I used XFS but the more I thought about it, I felt the ubiquitousness of EXT3 made more sense. Those Areca controllers seem to be smoking fast so I'm sure you're fine no matter what you do.

-Trouble