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Shared SCSI

This is a matter of the right hardware (in my case: HSZ50 controller (non-redundant) and a number of BA356 shelves that contain the disks - all 36Gb, officially, but this moment I have just one 1 Gb in it that holds the 8.2 installation.

The advantage is that ANY disk can be accessed DIRECTLY by all nodes connected to it, but you have to do something in advance, so MSCP won't be involved.

Storage

Hardware setup

Setting up the hardware is easy. A HSZ50 has 6 outlets - but you don't have to use them all. I use 1 and 2, the rest is empty (Cables hooked off the controller). The BA356 IO-modules must be set to 0 for the first from the controller (like I have done); if you hook up another BA356 beyond the first, the IO-module must be set to 1 - and so on.

Power it all up. First the BA356, then the HSZ50 (I don't know whether the order is relevant but it does make sense)

Configuration

First of all: initialize the controller to an initial state, if you don't know how it was configured before. It's a basic principle that you will have to work from a known state - and the only good one is " factory settings". Blank, in this case.

hsz> SET THIS INITIAL_CONFIGURATION

Now, define what type of use it has. for a HSZ50, it's a code - "A" = VMS, "B" = IBM, "C" = HSZ15 compatible, or "D" = WindowsNT.

HSZ> SET THIS HOST_FUNCTION=A

Next, define the ID's you want to support - these function as "virtual controller" that allows the OS to locate the units. (better: to define a unit, there must at least be one ID set up, otherwise you cannot even define units). You can use one Id, but more ID's give you more flexibility. You can use any number 0-7, but only four of them.

I kept it simple:

HSZ> SET THIS ID=(0,1,2,3)

Now you can add devices, telling the controller where each device is located.

HSZ> ADD DISK DISK100 1 0 0

The three numbers are the location. 1 = outlet#1, 0 = first disk, 0 = always zero.

This way, some space on the disk will be reserved for meta-data, so the disk cannot be used elsewhere. If you want to transfer the disk to another system, add "TRANSPORTABLE" :

HSZ> ADD DISK DISK260 2 6 0 TRANSPORTABLE

Now this disk can be taken out (withou impact to the controller!) and used elsewhere - as a normal disk. The disadvantage is that these cannot participate in a mirrorset, raidset or stripeset.

Tape devices can be defined as well - as "passthrough" - the very same way.

Now you gave defined your hardware, group them together as mirrorsets (something VERY different from shadowsets!), RAID sets or stripesets:

HSZ> ADD MIRRORSET M1 DISK100 DISK200 DISK300

HSZ> ADD STRIPESET S1 DISK101 DISK201 DISK301

HSZ> ADD RAIDSET R1 DISK102 DISK202 DISK302

and you can do a lot of them. But I haven't done it here.

Now you defined your storage units, it's time to expose them to the OS. This is done by defining units:

HSZ> ADD UNIT D100 DISK100
HSZ> ADD UNIT D101 DISK110

annd so on.

For DISK you can also use any other storage unit - mirrorset, raidset and stripeset.