Converting HVD Jamaica to LVD

[guest_1]

Is LVD and HVD cabling identical,
besides the 3.3V vs 5V difference?

Could we take a Jamaica and convert
it from an all-HVD to all-LVD solution
(no mixing)?

I.e.:
- replace all the disks with LVD
disks in the black enclosures, assuming
we use the pass-through DF connectors
inside the black enclosures (those
stomped "DF", yellowish, with no chips
on the tracks to convert SE to HVD)
- connect the Jamaica to an LVD card
(Ultra-2).

A big worry is that there is an Altera
chip inside the Jamaica enclosure
backplane which might be programmed
to see or force HVD signals. It's
not clear what it is supposed to do,
it's labeled with a part number #
"C3573-88001 rev D W2".

[Luk Vandenbussche]

LVD Disks are not supported on a jamaica box.

Jamaica box only supports SE and DF hard disks

[Zygmunt Krawczyk]

Hi guest :)

the fact is that almost all HVD Jamaica disks (except oldest disks) are LVD with LVD to HVD converters inside the black enclosures. But Jamaica backplane can run in SE or HVD mode only.

If you want to connect Jamaica to computer with LVD controller you may use external HVD to LVD converter.

Better solution is to buy new msa30 enclosure and new disks. The solution is very cheap and compatible with Windows, Linux and HP-UX servers.

Regards,
Zygmunt

[guest_1]

Luk,

It is not true Jamicas do not support LVD/SE
disks. Some of the black disk enclosures have
converters LVD/SE->HVD.
I've actually put U320 disks and it works.

All,

My idea was to use enclosures that do NOT
do that convertion, and use the box as an
all-LVD solution:
- Use an Ultra2 SCSI card
- Install LVD/SE disks
- Use pass through instead of converter
connectors in the black disk enclosures.

=> The only issue was: Does the Jamaica
enclosure itself has circuitry that is HVD
or SE specific (i.e. pushes 5V logic on
the SCSI bus). I checked and there's one
altera chip but it might do somethign else.

My guess is it'd probably work, worst
case reverting to SE mode, but most likely
in LVD mode, provided the HVD and LVD
SCSI cabling is similar.

Of course this is a poor man's solution
for an un-funded mini-web project with old
scrap parts :) Otherwise I wouldn't
bother and just order gear... I can't use
the HVD card (HP-UX A4800) for the Linux
PC I think (proprietary/no driver).


Original configs:

HVD 2GB disk - pass-thru-conn -> Jamaica -> HVD SCSI

SE/LVD 9GB disk - lvd2hvd-conn -> Jamaica -> HVD SCSI


Project:

SE/LVD 18GB disk - pass-thru-conn -> Jamaica -> LVD SCSI