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#7 "XFS" support possible?

Future Release
open
nobody
None
2
2004-06-21
2004-06-21
No

Hello,

First of all, I'll explain how I've come to this question.

We are using an audio editing system that works on a
Mac with additional cards with a SCSI bus built in. The
system originally was created on Unix, and ported to
the Mac about 15 years ago. The system uses its onboard
SCSI interface to write recorded audio to the disks.

Of course they also built a solution for easy backuping
the disks. This application (witch of course only works
in 9, but that's not the problem) mounts the disks on
the desktop when connected to the Mac's SCSI bus, or an
adaptec card, allowing you to copy files to other
disks. This is crucial to make exact backups (the
system uses non-destructive editing, saving the changes
to a file on the disk on your mac, leaving the data on
the file intact. Very handy, since only one backup has
to be made and different edits etc can use the same disk).

However, the disks mounted by that utility are very
slow (1 MB/s) on pre-G3 macs, and even slower on the G4
(0.5 MB/s). On the pre-G3s, the adaptec card speeds
things up a little.

If the disks are formatted in HFS, or HFS+, they get
speeds up to 20+ MB/sec, so, we came to the conclusion
the utility+extension to mount these "XFS" disks isn't
that efficient, so I searched for an alternative
utility that could do that, and found nothing, that's
why I post this here.

I have found out that Silicon Graphics has made
adaptions to that "XFS", but I don't think our disks
use that, since on a crash, or unexpected shutdown, the
system "rebuilds" the whole disk, witch takes up to
half an hour for an 18 GB disk, and even longer for
larger ones (it luckily never fails to "repair it",
must be the power of the "XFS").

Since it is very time consuming to backup data/restore
old data on all our disks, I wondered if it would be
easy to implement mounting this feature in your Ext2
mounter, and if it indeed would be faster. It is also
handy to run it in X because OS 9 rebuilds the @#)($*
desktop file everytime a "new" disk is mounted.

Thanks for reading, even if I'm afraid I already know
the answer, I'd like to hear your comments! And thanks
for the great work on the Ext2 mount/repair tools!

Discussion

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    Hi there, I'm an IRIX user, one of the few left. XFS on Linux is gimped, it's missing cluster and failover features, they never ported them. Other issues include how it interacts with the kernel API's, it was not designed for Linux, although their own engineers did port it. The biggest issue with XFS is not actually with XFS, it lies with the way PC hardware (x86) shuts off power, and I'm specifically referring to the power supplies not being robust. This is why people complain of corruption.

    On Linux, XFS fairs well against JFS (Ported from AIX) and ext2/3, it is actually preferred if you have a decent UPS system over the older ext filesystems. The performance you report is not with XFS, it is with how block copy allocations occur, not to bore you though, it's a messy project to port it to BSD, and they have been trying for years, it's mainly reverse engineering.

    Mac OS X' file system layer uses BSD code, and without a robust implementation on BSD, including NetBSD or FreeBSD, the most likely candidates for porting, it will never reach the Mac. Just see the big stir with Java SE 6.0 not being shipped with Leopard, people such as Gosling are jumping ship. The current unofficial X11-based Java 6 port is based on hybrid BSD patches and public sources, which are not legally allowed to be distributed in compiled form. The same thing happens to XFS, it's GPL licensed, it must run under FUSE because direct linking is against the copyleft (Liberal) license. To flip it around and stick it to them for being so stupid, OpenSolaris' DTrace and ZFS are under FUSE on Linux. The problem is Linux here, it stagnates cross-pollination, you're hard pressed to ever see something as old and widespread as ext or xfs under any other license than what daddy says it can be, the copyright holder has that right. SGI has also gone the wayside of development, they won't listen to a 10,000 person petition unless there's 10mln involved.

    Performance with FUSE is terrible because it's not running at the highest level, every operation is essentially interpreted by the user, and not the kernel itself. Unfortunately, ext2fsx might be doing something illegal if they are not using FUSE, and with that said, you must chose HFS+ or FAT32 if you want speed and reliability on Mac OS X. HFS+ is the fastest of the file system implementations. Oh, for the record, UFS in prior releases is next to useless, it was a fork of dated BSD code, before the FreeBSD project even was established, and it's not supported on Leopard.

    If you need to migrate your data, I recommend using a Linux livecd (Yeah, yuck) and a second external disk (Preferably USB, since SCSI's on Macs are too obscure)