Hyperdisk IDE SSD (DOM, DMV340)
Some notes about the HyperDisk 40 pin IDE DOM SSD
The Hyperdisk SSD is a solid state storage drive, intended for industrial uses. It's a very compact module that normally plugs directly onto the motherboards 40 pin IDE header (44 pin variants also exist). The module uses a small connector on the top to get 5 V power from the computer, and they supply a standard 4-pin molex adapter.
This disk is attractive for retro computing, since it's very compact and hopefully reliable. The performance is quite good, though most retro computers will not be limited by the SSD but rather the IDE controller.
I've tried two size variants of the DMV340, the 16 GB, and later the 64 GB variants. The 16 GB variants were used in retro computers, the 64 GB variant is used in my old world server as a legacy file server for e.g. the Mac II.
This is a somewhat typical Chinese designed product in that it has poor SEO, finding data sheets or the manufacturers website can be tricky.
I did dig up the datasheet for the smaller types (up to 8 GB): HyperDisk_DMV.pdf
This datasheet lists significantly worse performance than the current types, so it's definitely for an older variant of the module.
Power
The SSD is very compact, and uses relatively little power though for heavy use I recommend some airflow. It does feature temperature monitoring that can be read out using e.g. HD Tune.
Since the disk runs off a 5 V supply it's usually possible to grab power from a USB header or similar nearby, so I typically cut up the cable that is included and crimp on 0.1" sockets.
Overheating
I observed issues related to overheating when building the old world server (a fairly disk heavy activity).
When the reported SSD temperature exceeded around 70 °C, the SSD would stall out for several seconds at a time (stalling until the device cooled down?).
This made the system basically unusable.
Adding a chassis fan to ensure some airflow around the module brought the active temperature down to around 50 °C, which appears to be acceptable. I had no issues with stalling after adding the fan.
This module isn't super high power, but it definitely needs some airflow.
Bus
It does not appear to support sharing the bus, though I haven't tried hooking up two on a bus myself. This is one downside of the SSD, if you only have a single IDE channel you're not going to be sharing that channel with anything else like a CD-ROM.
This made it fairly impractical for my 486 with only a single IDE channel supported in the BIOS.
Performance
The speed listed by the eBay sellers of these disks is in the 80 MB⁄s read and 50 MB⁄s write range.
I initially only attained read speeds of 30 MB⁄s. This was also noted by the BIOS POST screen, which printed a message saying it had not detected an 80 wire IDE cable so it was using 40 wire mode.
HD Tune detected the drive as UDMA Class 6 (133 MB⁄s) capable, but the actual speed was class 2.
IDE cables are always 40 pin, but high performance cables are 80 wire with the 40 extra wires used as additional grounding to reduce signal crosstalk.
By convention, the motherboard detects this case by checking to see if pin 34 in the IDE connector is grounded. Since this SSD doesn't ground out this pin it's detected as a 40 wire cable and the IDE speed will be limited to around 33 MB⁄s.
In this case there's no cable, the SSD is sitting on the motherboard, using an 80 wire cable isn't even possible.
My old world server is the only case where I'm using this drive in a system where this difference matters, most retro computers can't do UDMA mode 6.
I soldered a strap to the motherboard side of the connector to ground out pin 34, and I was able to achieve around 70 MB⁄s speeds immediately. This also made a very noticeable difference to the responsiveness of the system.
The difference between measured ~70 and listed 80 MB⁄s speed is basically in-spec as far as I'm concerned.
Reliability
The disk appears to be using MLC flash, which is not surprising (some of the lower capacity types may use SLC according to the datasheet).
HD Tune diagnostics view showed the drive was reporting a few ECC corrections, and some other indications of minor flash wear.
For the price, I'm not expecting ultra high grade flash chips to be used.
I will note that the drive doesn't appear to be lying about the flash state, which is good at least.
For super high I/O applications it might be possible to wear out these disks, in that case you're probably better off e.g. using this as a boot drive and using a more expensive drive for the I/O stuff.
The reliability will probably be better than buying used IDE hard drives, in any case.