By Mike B. (additional tests by Joe Dylik)
Update: For more current articles on IDE RAID, see the related links below. Later articles tested the IBM 75GXP IDE drives which as of summer 2000, are the fastest IDE drives to date. The 27GB Maxtor drives used in the article below always seemed to have low write speeds. Also note that shortly after this article, Acard (and now Sonnet) sells a hardware IDE RAID card for about twice the price that may perform better. The Acard and Tempo RAID cards have switches on the card for configuring 2 drives as a single volume without needing to use Softraid drivers. Apple's drive setup sees the 2 drives as a single disk with the switches set to RAID striping on the card. However even the hardware RAID card does not offer impressive performance (compared to a single drive) based on reports, when used in pre-G3 Macs which have slower memory/PCI controllers and system bus.
After first testing IDE RAID (2 drive) in the 9600/350 with a G4/350MHz CPU Upgrade, I was very disappointed in the overall performance from IDE RAID vs a single drive. A good, fast single drive performed about as well as two drives in IDE RAID in that system. Since I knew from past testing that the Kansas motherboard design (9600/300, 9600/350, 8600/250 and 8600/300 systems) had low memory/PCI performance, I wanted to test in a more modern Mac model before passing final judgement.
Different drives than the Maxtor 27GB (ATA/66, 7200 RPM, 2MB cache) models I used may show different results. From the write performance, it looks almost as if there was no write caching on the drive. The higher density (10GB/Platter) Maxtor Plus40 drive showed literally identical Read/Write performance in tests with the onboard B&W G3, but I didn't have two of them to test for IDE RAID.
As you'll see below, even in the latest Apple G4/AGP system (as of March 2000), IDE RAID performance doesn't seem worth the extra expense of the RAID software and PCI card, especially if you have an ATA/33 or ATA/66 onboard IDE controller already. (Note that Joe's tests with two IDE controllers showed higher performance however, but that adds additional costs and uses up another PCI slot. Although the Seagate drives he used delivered more balanced Read/Write performance, their peak rates seemed lower than the Maxtor's in many cases.)
In the tests I ran, there was often little difference in single drive vs dual drive (RAID) performance, at least with the Maxtor 27GB (6800 series) 7200 RPM/2MB cache drives I used for these tests. Other drives may show different results as these seem to have much lower write performance than reads.
Listed first are my own real world and benchmark results, but below you'll find Joe Dylik's additional benchmark tests of ATA/33 vs ATA/66 PCI IDE cards using Seagate Barracuda IDE drives. He tested up to 4 drive RAID with single and dual IDE cards as well as single drive (non-RAID) tests. The results will surprise you I think. (Even Joe's results with dual cards is often baffling, as some combinations showed better performance with 2 drives than 4.)
This article includes links to my previously published guide to installing a dual drive RAID in a B&W G3 or G4 system. (See the Driveinstall and Softraid install pages linked at the top and bottom of this article).
All PCI IDE cards were tested in the middle PCI slot with ATA/66 cables. All disks were formatted in HFS+ (MacOS Extended). No boot time tests were run since striped RAID is not bootable at the current time in the new openfirmware Macs.
All RAID tests I ran used Softraid v2.2.1. This driver was also used in single drive tests with the PCI IDE controllers to compare Apple's OS 9 driver (Drive Setup v1.8.1) to Softraid's.
The following graphs show the results of tests with each of the cards and with various RAID software. Included are results with the G4's original Western Digital 20GB Expert drive connected to the onboard ATA/66 interface. You'll likely be surprised and disappointed in the results. For value, a single Plus40 (high density/high performance) Maxtor drive tested in a B&W G3 (ATA/33 onboard) delivered better sustained rates than any of the configurations shown in this article. (See the related links below for that review if you missed it.)
The graphs below show the results of the following tests:
Since a stopwatch was used to time these tests, remember there is some human error in starting and stopping the stopwatch so consider times within 1/2 second or so to be literally identical.
The Acard ATA/66 had a hair faster Read Peak Rate, but far less write performance, perhaps due to the Maxtor 27GB drive apparent lack of write caching.)
Update: After updating the Turbomax to firmware v1.7.4, Peak Rates in RAID were 30.16MB/sec Read and 23.73MB/sec Writes. This is a few MB/sec higher in R/W than with the v1.5 firmware.
Reads - Acard ATA/66 w/Maxtor 27GB (by a nose).
I didn't notice it until graphing the results at about 2AM, but the lower Turbomax RAID results compared to the same card with a single drive is odd. Due to the late hour I did not retest. And that's not a typo, the OEM WD Expert 20GB had exactly the same Read and Write rates (22.88 MB/sec).
Note how very little gain is seen from IDE RAID vs a single drive.
Update: After updating the Turbomax to firmware v1.7.4, Sustained Rates in RAID were 24.45MB/sec Read and 14.52 MB/sec Writes. (The firmware update provide a larger gain in peak rates than in sustained.) There does seem to be a 'hump' in the ATTO tools write graph that appears to indicate the drive's write cache is enabled although sustained rates are still far lower in writes than reads.
I ran both the standard Disk/Publishing Disk tests as well as the Random/Sequential tests. The PCI IDE single drive tests were run both with Apple OS 9's Drive Setup 1.8.1 drivers and with Softraid's drivers (denoted by 'SR'). RAID tests (dual drive stripe) used Softraid only of course. All disks were empty (freshly formatted) before the test.
(Practically a draw with the onboard IDE/WD Expert as scores can vary a few points run/run)
Update: After updating the Turbomax to firmware v1.7.4, MacBench RAID Disk score was 2277, Pub Disk score was 1636.
Notice only the Random Write scores really favored the IDE RAID (w/Acard ATA/66) in these tests.
Joe Dylik sent the results of ATTO Tools Benmark tests on an IDE RAID setup using up to 4 Seagate Barracuda IDE drives, with both one and two PCI IDE cards. Tests were run with both Softraid and FWB drivers (and in the case of single drive tests, ATTO's drivers as well). The results are very surprising. I'm not sure the ACard ATA/66 card had the most recent firmware update (released about the time Joe sent these results), but regardless his results are very interesting.
I asked Joe how he mounted the 4 IDE drives in the case:
He said he used the latest firmware available for the Acard and Turbomax cards. (My Turbomax card had an old v1.5 (spring 1999) ROM.)
Note: Where you see 'disk position' info, slot B/C means what position the card was in the Mac, slot A being the graphics card slot, B the next one over, etc.. Interesting to note that the PCI slot affected rates more than I'd have expected in some combinations.
All the Barracudas with the exception of the one on the Apple on board controller were set to Master position. The labeling B,0 and B,2 refer to the card position in the machine and the channel on the card.
Note in the table below that using two IDE controllers dramatically increases sustained performance. Also note the odd cases where 2 drives outperformed 4 drives with some driver/card combinations. (Compare the single card/single drive results farther down - some combinations of single card/RAID delivered slightly lower performance than one card w/one drive.)
(This table is wide so you may have to stretch or scroll your browser.)
Joe's Comments on his System and Results: Here's Joe's original mail titled 'Is the ATA/66 standard All Smoke and Mirrors?'
See the G4 onboard IDE tests page linked below for Joe's test results
comparing the OEM IBM IDE drive vs. a Seagate Barracuda and
the results of ATA/66 cable tests.
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