Introduction

Design and Operation Notes

• The box is made of moderately well built aluminum with plastic slide trays. The case takes up two adjoining half-height bays in the front of your computer. The bays must be immediately adjoining, some name brand cases put a gap between the two front-mounted 5.25" devices, rendering this device unusable (or at least, your case may need some modification). The case has notches which will permit installation in many boxes which have "fingers" on which each half-height device will sit. Many cases have an overhanging lip which will prevent the drive trays from being removed from the front of the machine with all the plastic in place. You need to decide how important this is to you.
• Two keys are used to "lock" in the drives. Both locks on one ACS7500 use either key (two are included) and all Accusys boxes examined so far use the same key. In fact, the locks are more a mechanical mount, the security of the lock is almost non-existent, as there are no tumblers in the locks. I'm of mixed feelings on this -- I don't like appearances of security when none really exists, but then, real locks would probably cause far more problems then they would solve.
• A number of LEDs give a very good status report on both the drives and the RAID array. LEDs are provided to indicate power to each drive, activity on each drive, redundant indication of the health of each drive, and a bar graph indicating how far along the mirroring is progressing. When the drive is in its standard operating mode, the remirror status bar graph becomes a scanning light, letting you know that it is alive and functioning. I'm very impressed by the light show this thing puts on -- in some ways it may be excessive, but I'll tell ya, the thing lets you know how it is doing. No question. If the array is degraded in some way, you will know it in no uncertain terms!
• The ACS7500 has a beeper which will help draw attention to it if it has a failed drive. The beeper is loud enough to be heard, but not very annoying, which may or may not be good (the ArcoIDE products have a beeper so loud, they put a "silence" switch on them). The Accusys box can be silenced simply by unlocking the failed drive. Apparently, if you have one drive unlocked, it assumes you know you are running in a degraded mode, and thus, no reason to be vocal about it.
• There is one large fan that pulls air across the drives. I am very pleased with the temperature it keeps the drives -- a pair of 80G drives were kept at "barely warm" (by finger) temperature. The fan does make noise, but not unreasonable amounts for any system which is likely to have multiple drives in it. The tone of the fan is not unpleasant to me. (however, in the move to "quiet PCs", this may be much louder than the rest of the system. I have heard one complaint from a home user who added it to their home system).
• Early ACS7500 boxes had no provision for the new "Big Drives" extension to the IDE standard, the standard used on newer, larger than 137G IDE drives. The most recent box a client of mine bought had a note stuck in it which says, "ACS-7500 now supports Big Drive (ATA-6) and you can install any hard drives with capacities over 137G ...". There is, unfortunately, no upgrade for the old ACS7500 boxes. Accusys's web site does indicate how to recognize which ACS7500 boxes are "Big Drive" compatable, it is not obvious from the box itself, although later ones have the model number ACS75130 instead.
• The ACS7500 can be used to duplicate a disk, and potentially, could be used to "upgrade" a disk pair. This is done by removing one of the drives in an existing pair, mirroring the remaining drive against a bigger drive, and then removing the remaining smaller drive and replacing it with another larger drive, and remirroring (again). At this point, the ACS7500 will report a "larger" drive size to your system on the next reboot. What you can do with this system depends upon your OS. If you have a semi-intelegent OS (i.e., OpenBSD), you can alter the partition table and disk label and add new partitions. Other OSs (Windows) may be able to have existing partitions "expanded" using a program like Partition Magic. It is important to understand, however, that being an OS ignorant device, the ACS7500 isn't going to do a thing to help you expand your OS into the new disk space, you are going to have to figure that out on your own.
• Compaq users may have some issues. I have found that some Compaq systems have very weird drive translation geometries, and (related?) the ACS7500 will not properly establish a mirror if attached to the Compaq computer at power-up. A workaround for this is the following:
  • Unplug the ACS7500 from the IDE cable, apply only power to it.
  • Establish the mirror (i.e., "lock down" the second drive). the box should start mirroring now.
  • Power down the box (no need to wait for the mirroring to complete)
  • Plug in IDE cable, power box back up, remirroring will resume.
• When remirroring, the ACS7500 will blink at a rate that roughly tells you how it is doing with remirroring. If you find it not blinking, you have an unhappy ACS7500, see the Compaq issue above. Odds are, it probably *is* blinking, just very, very slowly, one was seen to be blinking at roughly a half-hour on, half-hour off, and then it gave up the mirroring. If the machine is busy using the hard disk while the mirroring is taking place, I have noted the blinking slowing.
• It *may* be wise to disable write-back caches on the drives before using them in the ACS7500, though Accusys makes no statement about this. I know people who consider it a requirement to disable write-back caches on disks in general. Not a bad idea, though at a significant performance penalty.
• Rebuilding a mirror takes time -- a 20G drive takes around an hour and a half, an 80G drive takes around six hours. System is operational at this time, performance is somewhat degraded, but not horribly. Buying a 160G drive when you need a 30G drive "just because it was only $20 more" isn't a good economy when mirroring drives, the remirror time will make you regret over-sized systems.
• Netware 3/4 notes: The Accusys 7500 box and Netware's IDE drivers are very unhappy with each other. Performance while remirroring is basicly ZERO, and in fact, if anything attempts to write to or read from the disk, the server will tie itself up in knots until it ABENDs. I have no idea what is going on here, a wild speculation is that the IDE driver is querying the "drive" and the drive is continually saying, "yes, I'm not idle". It just acts like Netware doesn't want to disturb the drive. DO NOT USE THE ACCUSYS BOX DIRECTLY WITH THE NOVELL IDE DISK DRIVERS. Netware can not be running while the system is remirroring. Once the mirror is complete, however, it WILL run just fine, but that very much defeats the purpose of this box. Fortunately, there is a very simple solution: use a third-party IDE driver. I have found the Promise UltraDMA cards have their own Netware driver which instantly and completely resolves this problem, and for about $50, it makes the Accusys 7500 an ideal partner for a Netware server. I found the Promise driver very easy to work with, though being a .HAM driver, it does require your Netware 3 server be fully patched. You can retrofit the Promise driver onto a drive set that was created without it.
• I have received a report that at least some motherboards have trouble with these devices. Other than the above mentioned Compaq systems, I don't have much more hard info on this, but I'll be keeping my eyes open for more info and experiences on this.
• Accusys actually DOES have a "support" section on their website, here. Not sure if I never noticed it before, or if it is new. User interface is kinda strange, but there are a lot of odd bits of info there.
• At least the new 75130 boxes can be monitored through software, either through the ATA interface, or via a three-pin serial jack hiding on the back of the drive (over the master/slave jumper). Looking for more details on this. I'll report if I get them.

Management software

Further, my success with the SATA devices has been very poor -- the Accusys software could not detect an IDE interface to talk to the drive, my guess is that is due to hardware specific SATA drivers obscuring the interface to the application. However, they may also be aware of this problem. Curiously, the SATA versions of this application include the serial cable. Unfortunately, the machines I really wanted to put this in had other needs for their only serial port, so this also proved to be a problem.

I have some reason to believe it may be possible to monitor this device in other ways, other than the web browser and webserver.

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Published: 04/06/2004

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