eric@milo.UUCP (09/21/84)
I recently received information on a new product from System Industries that supports multiple machine access to their disks. They also claim to have Unix support for this. The name of the product is "SIMACS". The natural question is - has anyone tried this yet? We are looking at enlarging our installation (more machines) and the ability to share disks (and even the data on the disks) between machines sounds very good. But it seems to be an extremely new product, at least for the Unix world. If there are any responses (and enough interest), I'll post the results. -- eric ...!seismo!umcp-cs!aplvax!eric
kds@intelca.UUCP (Ken Shoemaker) (09/23/84)
We had this beastie on two of our VAXes about a year ago that I had
the misfortune of working on. At the time, they didn't have unix
support (not that it would have made much difference) so the machines
were running VMS. There were a couple of problems, none the least
of which I could attribute to our VMS crew not quite knowing how
to configure the systems to which it was attached. However one
of the really fundamental problems I'm not sure Unix can approach
any better, and it was a real performance killer. Consider two
machines having write access for a single disk. For normal
files perhaps it wouldn't cause too many problems, but for
directory files you could have some nasty problems. With
the kernel running on a single machine it has just one
place where disks are cached, but with two machines doing
the same thing, it can get kinda funky. As a result (at least
for the VMS machines) one machine would hit the other machine
to dump out its disk buffers whenever it wanted to do anything,
and semaphores were kept on the disk itself. Anyway, high
performance it ain't.
In addition to these problems, I would make sure that the unix
support is available. They were promising this last year, but
last I heard, it was still "vaporware" (not that I'm casting
aspersions, but a word to the wise....)
--
I've got one, two, three, four, five senses working overtime,
trying to take this all in!
Ken Shoemaker, Intel, Santa Clara, Ca.
{pur-ee,hplabs,amd,scgvaxd,dual,idi,omsvax}!intelca!kds
---the above views are personal. They may not represent those of Intel.mather@uicsl.UUCP (10/14/84)
The people from SI keep calling me and telling me that UN*X supported SIMACS is 'just around the corner'. I personally think that there will have to be some heavy wizardry involved to keep up disk integrity. We are watching the VMS people across the street with their SIMACS running VMS. They only have one VAX now, but the 2nd is on the way. They have the CPU on one side and the Eagles on the other. That works great, I am told. The real fun will begin when their other VAX rolls it! Let the other guy try it and see! If it works well, this could open up a lot of possiblilities for us. b.c.mather software surgeon uiucdcs!uicsl!mather
haral@ttidcb.UUCP (Haral Tsitsivas) (10/18/84)
I have had a System Industries salesman call on me last July about SIMACS,
and again about a month ago. From what I hear they are in Beta test right
now, and expected to finish Beta test in late November. It seems like
a great idea if it would work as advertised. You could connect a controller
with up to 8 VAXens (each 9920 controller has 8 drives) which allows you to
distribute load among your VAXes easier. Of course you still have
a system disk on each VAX for booting and /. I would like
a technical person from SI to confirm the release time though, since
timing information may be wrong with the sales force.
--Haral Tsitsivas, TTI, Santa Monica
...!{philabs, trwrb, randvax, vortex}!ttidca!haral