Find SSD on SCSI? It might be time for 3000
July 17, 2012
SCSI remains the primary method to connect disk to HP 3000s. That means that most of the Solid State Disk (SSD) memory-based devices won't serve for MPE/iX storage. But it's not impossible to make the quantum leap from rotational to RAM storage. It might be worth the experimentation, given the upsides. In short, if a manager can find the SCSI, honey, find the time -- to experiment.
Starting at about $250, the devices are not costly anymore. And even in the more-rare SCSI units, 120-480 GB models are available in online stores.
"You would need to find a SCSI SSD," said Larry Kaufman, a systems engineer with BayPointe Technology. "They are out there, but there are not a lot of choices. Here is something to consider: When a SSD fails, the failure is likely to be catastrophic, with total data loss. HDDs can fail in this way too, but often give warning that they are failing, allowing much or all of their data to be recovered."
Kaufman offered a note about the old HP's "silverback" disks used with 3000s. "They would make tons of noise for weeks, sometimes months, before they would die."
That sound of rotation is also the sound of slower operation, of course. Once you go non-rotational, you won't go back, said one consultant. Using SSD tech in a 3000 carries the usual warning that was often quoted in the 1990s and onward: This is a storage unit not tested for MPE/iX. But there's plenty of tests not yet performed for SSDs. Like any advanced technology, SSD has also got some emerging downsides now being discovered in the field.
Arrays help extend these Mean Time Between Failures and offer hot-swap. The 3000's array choices run to the XP and VA models from HP. It can be surprising to see that some well-schooled 3000 managers haven't explored array choices yet. Everybody has something to learn, whether it's RAID or IPv6.
There's also some experimentation going on with setting up a redundant array of SSD units. One tech white paper reminds users that the TRIM command for controlling SSDs should be supported in order to array SSD units, and that older operating systems usually don't TRIM. And by older, the paper's author means Windows XP, which was last released about the time MPE/iX was getting its last disc design. No TRIM in MPE/iX, of course.
The question for the typical 3000 manager is whether SSDs are more reliable or less reliable than hard disc arrays. Choosing XP or VA arrays is a more commonplace storage upgrade for HP 3000 storage configurations. On that subject, Craig Lalley -- who lives to update your 3000 storage -- arrayed the choices.
You could put an XP array with 128GB of cache as a disk subsystem. HP has a whole line of these high speed fault tolerant arrays: XP256, XP512, XP1024, XP12000, XP24000 and a name change to the newest P9500. They all work with MPE. They have software options that provide "hardware mirroring across the WAN", local mirroring and snapshots.
The XP array is much newer, in that they are still making them and the models get updated every other year. Also the XP array is extremely fault tolerant, it is built to be set up, turned on and never turned off.. You can add cache, replace boards without losing data or host connectivity. The VA array only holds 4GB of cache, 2GB per controller.
The XP is several steps above the VA (to put it mildly). You can literally connect hundreds if not thousands of hosts to an XP Array. Comparing an XP array to a VA7410 is like comparing a VW Beetle to a Formula 1 car.
There's a similar speed increase available by moving to SSD. Native support for SSDs on the 3000 was being explored as far back as 2009 by one indie support company. In the current state of the art, the best way to exploit this new storage technology for MPE/iX will be using the Stromasys HPA/3000 emulator. It employs whatever storage is attached to the Intel i7 Core PC running the emulator.