View Full Version : Hardware RAID in Mac OS 9.X

Shallow Hal
05-30-2002, 04:05 PM
I'm looking to build an IMAP e-mail server using a G4 Desktop. I'd been planning on doing a drive mirror with SoftRAID (since Software doesn't support past RAID Level 1 at present) and two fairly large Seagate SCSI drives, but I was wondering if there were any Hardware RAID options I could consider? And is it worth the expense in terms of performance?


05-30-2002, 05:07 PM
From what I've read, the PCI card IDE RAID systems seem to be working well - We've gone a bit further out using an SCSI-IDE backplane to create a 500 GB RAID 5 array - we used an Arena Raid hardware box - it's connected to a Miles2 on a 7300/200/G3/333 ASIP server under 9.1 and it's been very good. Performance is quite good actually for our LAN since all the RAID control is on the box's hardware and not taxing your processor as it would if you were using a software RAID.


05-30-2002, 07:07 PM
Hi Hal,

If you are looking for fast redundancy then a ATTO host card and a couple of Seagate Cheetahs is the way to go. You'll pay a tiny amount for the mirror in overhead but the ATTO Cheetah combo screams. SoftRAID 2.2.2 is definitely the best RAID driver.

Be thinking in terms of backups. You'll need a good backup plan for all the other faults that can plague you. A hard drive failure is one of the least likely, although with a mirror the easiest to handle.

There is also a ATA hardware mirror device. It's available at: http://www.duplidisk.com/productspages/pcimac/pcimac.html

Not as fast as SCSI but absolutely zero overhead since it is just a data line splitter.


Shallow Hal
05-30-2002, 07:18 PM
Speed is absolutely an issue here, as I will be running an IMAP E-mail server on the machine. Disk write speed is critical above all else, which is why I want the fastest possible SCSI performance possible (within a reasonable budget, I'm not going to spend $10,000 on an external RAID enclosure).

Redundancy is important to guard against disk failure because it's an IMAP server - if a disk fails, everybody's e-mail just went bye bye. I've done some reading today on the pitfalls of RAID 5 versus RAID 10. RAID 10 is really not an option because the Desktop G4 is going to accommodate three drives internally at best and as I've said, an external drive enclosure doesn't make sense for us for the anticipated use and cost.

I'm starting to lean towards a disk mirror, combined with disk cooling (since both disks will be mounted fairly close to each other). My concern is getting the fastest possible disk write performance, which I suspect would come with a hardware RAID controller, unless the disk mirror process just isn't that processor intensive for SoftRAID to deal with.

05-30-2002, 09:13 PM

Nothing beats an ATTO and a Cheetah. In hardware RAID0 we can easily reach PCI bus saturation with 3 drives.

No other single drive will be close. In a RAID1 mirror you will lose a tiny percentage of overall performance in the maintanance of the RAID, but it is relatively insignificant. There are no SCSI hardware RAID1 controllers for internal use that I know of.

Even with the small overhead in softraid, scsi mirroring still beats by a fair amount ATA hardware mirroring.

An ATTO UL3D and two current Cheetahs with Granite cables and termination is as good as it gets internally both reliability and speed wise. You will NOT need extra cooling in the current G4 case, Cheetahs aren't too bad temperature drive's.

You will want to keep the two Cheetahs in the single drive brackets, I don't advise you to stack 10 or 15k rpm scsi drives. There is a company that is making a fan cooler mount that will fit in there. I've never used them and the name escapes me.

Again, drive failures are the least likely failure and well covered by a mirror, a comprehensive backup plan should always be included in your planning to account for the more common problems. I would always recommend a network connected backup cloning to another computer and retrospect archived backups also.


[This message has been edited by ricks (edited 30 May 2002).]

Shallow Hal
05-31-2002, 06:03 PM
Thanks for all your followups.

First of all, ATA/IDE is not an option because of speed concerns.

Second, I'm confused by what you mean about mounting the drives in the single drive brackets. There is only one stacked drive bracket in our G4 desktop - the only other potential available space to even fit a drive would be under the CD Rom drive, which doesn't appear to be built for mounting a hard drive. If I mount two drives there, should I go with the Barracudas instead of the Cheetahs to mitigate heat concerns?

So here's what I'm thinking on my configuration.

I'm going to open up the G4 desktop machine and remove the standard ATA drive from the stacked bracket (there is only one hard drive bracket in this machine at the bottom of the case below the fan). In its place, I will mount two Seagate Cheetah 18.4 GB Ultra160 drives (ST318406LW) or two Seagate Barracuda 18.4 GB Ultra 160 drives (ST318437LW), depending on potential heat concerns. These will be connected to an ATTO UL3DS SCSI card (my understanding is that SoftRAID does not perform faster on a dual-channel SCSI card) with Granite internal cabling and proper termination.

I will use SoftRAID 2.2.2 to manage a RAID1 Disk Mirror.

FYI, for backup, we use HP backup drives and Retrospect Backup to backup all our servers, so we will be able to backup this server in addition to the disk mirror.

Does this sound like a plan?

[This message has been edited by Shallow Hal (edited 31 May 2002).]

06-01-2002, 07:10 AM
You should have three spots for drives. There should be The stacked bracket in the rear The one below the big fan and one more below the power button assembly allowing you three drives across the bottom of the case


Damien's Stuff (http://www.macmeisters.com/Damien/)

06-01-2002, 10:48 AM
Damien is correct. There is mounting brackets for four total drives in your computer.

I would NOT remove the IDE drive, in fact I owuld keep all my OS, Applications and replaceable stuff on the ATA drive and save the mirror as simple email storage. Way easier to administrate your mirror that way.

YOu will see drive size brackets in the floor of your computer with a single screw holding each of them in. You will also find a pair of extra power connectors available.

That should work great.


Shallow Hal
06-03-2002, 12:36 PM
I see what he means - the two adjacent spaces next to the stacked bracket. Duh.


You guys have been super helpful. Hopefully, I will be placing an order for all of this stuff soon with Mac Gurus. This is a great site and you've been very helpful.

06-03-2002, 03:11 PM
A pleasure. http://macgurus.com/infopop/emoticons/icon_smile.gif Rick

06-03-2002, 04:30 PM
There is a review on www.xlr8yourmac.com (http://www.xlr8yourmac.com) of using 3 U-brackets in G4 tower for total of six drives - the hardest part is having Y-power adapters and cables plus PCI IDE cards. BUT, it _can_ be done!