MattG's picture

Dealing with Defrag

For most of you, defragmentation has become a regular practice in the administration of your Xsan volume. At some point, either capture files, or more commonly, render files are becoming so fragmented across the breadth of the storage that their playback predictably yields dropped frames.

The solution, of course, is to run the snfsdefrag utilitity, found in /Library/Filesystems/Xsan/bin, or to use the handy Xsanity Defrag program, Xsanity's cocoa wrapper of the same utility, in order to address the issue. [Ed. Note: Our Xsanity Defrag is getting old and creaky, and we do not currently recommend it!]

The snfsdefrag utility, used in its simplest form, gathers all the fragments of a given file (called “extents” by the utility) and places them in a section of the free space of the storage in one continuous chunk. The “virgin” territory that it usually seeks out in order to do this is the “far end” of the storage pool, which would usually not fill up until the storage pool itself reached its maximum capacity.

aaron's picture

New PowerMacs with PCI Express and dual Gig-E ports

Apple today announced new PowerMacs. The architecture new features two Gigabit Ethernet ports on the motherboard, a 100% increase, which is great for Xsan. The PCI slots are now PCI Express, which is not backwards compatible with PCI or PCI-X. So you'll need new Fibre Channel HBAs for these new Macs. Apple says they are shipping their PCI Express HBA in 3-4 weeks.

xadrdm's picture

How to split up this 7TB Raid?

Right off the bat, 4 systems editing a feature film at DV50 @ 23.98 fps (~6MB/s).

7TB Xraid in the mail (along with the entire Xsan setup). Can't afford anything else until we sell this project.

Take 2 drives for MDJ, that leaves 5 on one side. Remove 1 for Hot Spare. So I have 4 drives ~ 2TB. ....But then how to treat the other side with the 2TB limit on a LUN?

OR, can I split that MDJ pair across the two controllers? Which would leave me 6 drives per, down to 5 with HS, which might be sub 2TB after RAID 5?

Thanks for clearing up my brain!

brandon's picture

Xserve RAID Admin Tools 1.5 available

Apple made 5MB of fresh meat available today for all you early adopters. Get your hands on Xserve RAID Admin Tools 1.5 Update via either Software Update or the standalone installer. Along with a pretty fair list of new features and a few fibre channel compatibility updates, the release brings some new procedures for adding and moving drives and arrays, as well as for replacing controller modules. The update is recommended for all Xserve RAID users; still, spend an appropriate amount of time with the README -- wouldn't want to hurt yourself out there on that cutting edge.

aaron's picture

Free your blocks!

UPDATE: The premonition about fragmentation was correct. The morning after the pruning was filled with dropped frames. Be careful using this operation on volumes used for video storage.

When you write files to an Xsan volume, an application can ask the metadata controller to preallocate a certain number of blocks on the filesystem. But you may not end up using all those blocks for data. To quickly recover that allocated, but unused, space, type this command:

sudo snfsdefrag -rvp /Volumes/XSAN

Instead of "XSAN" type the name of your Xsan volume. On one 14 TB volume that was a bit less than half full, I recovered 700 GB. (Of course, that space is going to be pretty fragmented.)

xadrdm's picture

the XRaid I need.

I will be serving 6 edit stations, editing DV footage. They will be using a maximum of 3 (although BY FAR the average is 2) streams of video. Will one xraid and xserve be sufficient? i'm very new to this process and would apprciate any guidence ANYONE can offer.


saa2012's picture

How to restart XSAN on client without reboot

This morning I came in and my fileserver didn't have the XSAN volume mounted. XSAN Admin reported that the XSAN file system is not running. I have 15 people logged in at this point (network homes). If I possibly could what I would love to do at this point is simply restart the XSAN client daemon but my knowledge is insufficient. Of course I had to just reboot because I couldn't see any other way but I'd rather not cause this kind of disruption in future.

After restarting I can see in the process list the following:

694 ?? S 0:07.10 /Library/Filesystems/Xsan/bin/fsmpm -- -- /Library/Filesystems/Xsan/debug/fsmpm-sync.478

This seems to be the agent that needs to run (fsmpm) but I'm unsure if I can simply paste that line in. I tried to man fsmpm but there seems to be no man page. I don't know what the significance is of the fsmpm-sync.478. It looks like it might be a dynamic value. I'd hate to mess something up. Does anyone know how to bootstrap XSAN on a running server where XSAN has simply quit itself?

brandon's picture

Retrospect 6.1 adds Xsan support

EMC Dantz tiptoes into support for Xsan this week with the release of Retrospect 6.1 for Mac, a free update for Retrospect 6 users. The release notes convey a whole laundry list of caveats, though — don't install it on the SAN itself, forget about creation dates, forget about Access Control Lists, forget about subvolumes, expect some compare errors. Still, promising, and I'm sure we'll give it a try here ... meanwhile I'd welcome any backup stories from those of you using competing products, successful or otherwise.

bforcier's picture

Mirroring a 20TB volume


This might be a double post so please bare with me if it is (the original one seems to have disappeared)

I need to build a 24/7 Xsan volume of 20TB capacity with zero downtime (it cannot have any potential hardware break points failure for 65 days in a row)

I know I can build it around using multi Xserve RAIDs, 3 MDCs, redundant pathways for GigE and FC, and redundant pathways for electricity but the controller in the Xserve RAIDs is still a potential breakpoint...

Now, what I would like to do is some sort of volume or LUN managment in front of the MDCs so does anybody know if Veritas' solution for LUN mgt or JMR's Datamover would do it?

Using those technologies, I guess I would replicate the LUNs on the SCSI block level before they are managed by the MDCs?

Or am I going at it the wrong way?

Thanks for any input you might have!

brett's picture

Searching XSAN Volume via Sherlock in OS9

Now before anyone spits fire at me,

I have Xsan setup as the datacenter model. I have several NAS heads that connect to the storage on the backend and share out the data thought different fileservers. Clients are OSX, OS9, and Windows.

Heres my question: I have OS9 users complaining about using sherlock and how slow it works or that it doesn't.

I know that there are bugs in trying to do this but does anyone have any ideas on what can be done to allow users on Mac OS9 to perform searches on the mounted Xsan sharepoints any quicker?


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