View Full Version : Raid support in Tiger

05-02-2005, 08:51 AM
The Tiger web pages say that Raid support has improved but they do not mention anything about Raid 5 support. So I assume that users must find non-Apple solutions if they want Raid 5.

Can anyone confirm that Tiger (10.4) does not have Raid 5 support?


05-02-2005, 09:25 AM
Well, I can't bet my life on it, but I would bet a chunk of money. No RAID 5. Too CPU intensive, plus other I/O issues....

I think they have simply added some RAID 0 and 1 features to 10.4. If you need RAID 5, then you really need a hardware solution, and if you want full featured RAID 0 or 1, then SoftRaid (http://www.softraid.com/index.html) is still the best thing going.

05-02-2005, 09:42 AM
There was a really good review of (pre-) Tiger features and applications, including Disk Utility, with a comparison of Tiger and SoftRAID, that was very complimentary of both.

Disk Utility: Mac OS X 10.4 - Part 15

The article got pulled. It had something like 14+ installments before that happened. Unfortunately, I didn't download it to disk. But I recall that some things now in SR3 only were going to be available, or planned for. One of which was the ability to have multiple volumes, set the stripe block size.

I don't know the status of SoftRAID Pro, but just adding 0+1 is a major step and has had to wait.

ATTO posted ExpressStripe 3.01 in order to work better with Tiger. SR 3.1.3 has as much pre-Tiger compatibility as could be done, with any software OS update and the possible changes.

This 3.1.3 release is an important bug-fix release. We also continued to make improvements towards being Tiger compatible, and we will be ready with a Tiger compatible release when the time comes.

For now, I am leaving my RAIDs off-line and plan to test just how good ATTO support is going to be installing and booting off a test drive today or tomorrow.
MDD G4, ATTO UL3S/D (retail) and an older Cheetah 10K.5.

The next step, to see if Tiger works on Adaptec 39160. That combined broke with 10.3.9 on MDD but maybe not on B&W (where I usually use it).

Some of those inexpensive "ATA RAID" cards like SIIG and Sonnet or even non-RAID may have to have firmware updates. In fact, while some PCI cards work better now (deep sleep support), others are proving to be trouble (Adaptec again, 2906 and 2930 may have been dropped, even OEM cards). While SeriTek 1V4 has better support (hopefully FirmTek was working with Tiger support rather than have to do so after the release of 10.4, but past experience is not to rely too much on Apple, things that worked up to later builds might still not work or change with the GM version).

With all of the changes in 10.4, I would expect changes and improvements in the underlying filesystem and disk I/O to improve performance.

05-02-2005, 12:14 PM
And here is a short review of DU RAID features from over at afp548.com:

AppleRAID 2

While technically not just a server tool, Apple's RAID software has received a lot of attention in Tiger. Some highlights include:

The ability to set the block size of the RAID. By using this feature you can tune your RAID set for the best performance. You can also now use any volume on a disk to create a RAID, not just the devices themselves.

Mirroring has received the most updates, you can now tell a mirror to auto-rebuild itself in the event of a failure. Making this feature even stronger is the ability to designate spare drives for the mirror sets. Another key mirror update is the ability to easily split a mirror for an instant backup of your file system. This has been a general practice in data centers around the world for years and now we can use the same strategy.

A new "RAID" type in Tiger is a concatenated set. This pseudo RAID level allows you to combine drives into one larger volume. Like a mirror, you can start the concatenated set non-destructivly but you will loose the data on each drive you add to the set. To be honest, this option puzzles us a bit. It has all the fragility of a stripe, with none of the speed gains. I think that Mac OS X would be better served with full support for union mounts instead, but that's for another day.

Another new feature is the ability to nest RAID sets. This allows for mixes such as 0+1, 1+0, and you can use concatenated disk sets inside your RAID arrays.

All in all, AppleRAID is a much stronger part of the OS now, and one that all sysadmins should take a hard look at. Especially the ability to split off a mirror set drive is going to open up a whole set of backup strategy changes.

05-02-2005, 12:31 PM
The article is Tiger Server Overview (http://www.afp548.com/article.php?story=2005041722220621)


05-03-2005, 03:22 PM
And here is a short review of DU RAID features from over at afp548.com:
Thanks Unc!


05-03-2005, 03:35 PM
My pleasure. TZ's link is the full article which is great (as usual, TZ is on top of things). I usually try to link to the source...sorry. :o

05-04-2005, 10:45 AM
SoftRAID 3 driver included with Mac OS X Tiger

SoftRAID today announced that its SoftRAID 3 driver is included with Mac OS X 10.4 Tiger (both retail and CPU-installed versions).

The SoftRAID 3 driver allows Mac OS X to recognize SoftRAID volumes created with the SoftRAID 3.

"This means that a user can take their SoftRAID volumes to any machine with Tiger installed and the volumes will appear on the desktop and function normally, with or without the presence of the SoftRAID application. The application is necessary to create and manage the volumes."

The company also said that users can install Tiger directly onto their SoftRAID volumes without modification.

Version 3.1.3, the currently shipping version, is recommended, for Mac OS X Tiger; however, a future version, due later this month, will address CD/DVD creation issues in Tiger.

The full version is $130 (electronic) or $150 (CD)