[geeks] Idea - 2.5" to 3.5" SCA adapter carrier

[Mark Benson]

Ha! Well... firstly I'm surprised few of you know 2.5" SCA SCSI Disks 
exist! Yes, they were short-lived and frankly got replaced by SAS in 
most applications very quickly but legacy drags on in some quarters and 
U320 SCSI remained a thing for longer than it should have (hello, IBM). 
I am *pretty* sure only Seagate made them and only IBM ever used them in 
any numbers, apparently in their eServer X-series machines. BUT that 
means that there are still plenty available used and the prices are 
comparable with 3.5" drives due to them being less use to people looking 
for used server parts. They are all 10k drives but are very quiet, which 
is one reason I grabbed a load a few years ago. The only Nota Bene with 
these is they do NOT work on older narrow SCSI buses. They must be 
fitted on a suitable Ultra-Wide SCSI bus. The older stuff gets the more 
sketchy it gets as to working, but I suspect late 3.5" SCAs are just the 
same. I have had them work on a a AHA-3640 in a Windows PC and also on a 
Sun Symbios PCI card in a SPARC, however. I haven't tested them as far 
back as a SS20, however. Frankly, for older stuff SCSI to SD adapters 
really trump these anyway...

So, I drew up and mashed together the first prototype and wadayaknow! It 
works a charm. I've refined the design a bit and am going for a version 
2.0 which will be nicer to fit and cleaner. I tested them in a Sun 611 
(yep they have bottom AND side mounting holes!), IBM POWER Series SCA 
drive carrier (the one with the edge connector at the back) and a HP 
standard SCSI disk carrier (in my case used in my zx6000). I will dig 
out a spud and make sure it fits my Sun 711 too, definitely test fitting 
one in the SS20 as well as that things' CRYING out for a decent quiet 
SCA disk (as long as it actually recognises them!).

Largely speaking, given a couple of engineering drawings (taken from the 
manuals of a 2.5" and 3.5" model of drive) and a day with verniers and 
some squinting (mostly to sanity check the manuals) it wasn't that hard 
if you've got any grasp of CAD drawing in 3D (or in my case have a very 
easy to use CAD program). The 3D printing part is my Dad's area of 
expertise at the moment, I'm learning but right now I'm happy just 
drawing up meshes for him to throw at a GCode compiler. There's some 
warping at the ends but it thankfully didn't effect the fit, I'm told 
that's likely shrinkage or poor bed adhesion (both 'one of those things' 
you tackle in 3D printing).

In the (apparently!) rare and remote possibility anyone wants to print 
some, I will up the STL files somewhere once I'm happy with them. Thes 
don't work for SAS and SATA drives in slide-in trays because they won't 
offset the drive correctly (SCA is centre aligned, I will NEVER KNOW why 
SATA/SAS isn't, that was really rather stupid IMHO). They will of course 
work for fitting 2.5" SSDs and suchlike into PC 3.5" bays which are 
cable-attached but might be considered overkill, and adapters for those 
are 2-a-penny.

Have some pictures. I know everyone loves pictures! This is the drive 
and trails fitted to a HP 3.5" carrier (which I plopped in my zx6000 and 
it saw the drive 100% fine). I also included a couple of screen shots of 
the 3D file of version 2.0.

https://www.dropbox.com/sh/y87ksa66uv86h0u/AADyfMN9JpLAzF7s_5k8RgUsa?dl=0

Happy days. I did a thing!

-- 

Mark Benson