Al Hopper wrote:
On Fri, Dec 4, 2009 at 1:06 AM, Erik Trimble <erik.trim...@sun.com
<mailto:erik.trim...@sun.com>> wrote:
Hey folks.
I've looked around quite a bit, and I can't find something like this:
I have a bunch of older systems which use Ultra320 SCA hot-swap
connectors for their internal drives. (e.g. v20z and similar)
I'd love to be able to use modern flash SSDs with these systems,
but I have yet to find someone who makes anything that would fit
the bill.
I need either:
(a) a SSD with an Ultra160/320 parallel interface (I can always
find an interface adapter, so I'm not particular about whether
it's a 68-pin or SCA)
(b) a SAS or SATA to UltraSCSI adapter (preferably with a SCA
interface)
Hi Erik,
One of the less well known facts about SCSI is that all SCSI commands
are sent in legacy 8-bit mode. And it takes multiple SCSI commands to
make a SCSI drive do something useful! Translation - it's s-l-o-w.
Since one of the big upsides of an SSD is I/O Ops/Sec - get ready for
a disappointment if you use SCSI based connection. Sure - after the
drive has received the necessary commands it can move data blocks
reasonably quickly - but the limit, in terms of an SSD will
*definitely* be the rate at which commands can be received by the
drive. This (8-bit command) design decision was responsible for
SCSIs' long lasting upward compatibility - but it also turned into its
achilles heel; that ultimately doomed SCSI to extinction.
Really? I hadn't realized this was a problem with SSDs and SCSI.
Exactly how does this impact SSDs with a SAS connection, since that's
still using the SCSI command set, just over a serial link rather than a
parallel one. Or, am I missing something, and is SAS considerably
different (protocol wise) from traditional parallel SCSI?
Given the enormous amount of legacy hardware out there that has parallel
SCSI drive bays (I mean, SAS is really only 2-3 years old in terms of
server hardware adoption), I am just flabbergasted that there's no
parallel-SCSI SSD around.
I understand exactly the problem you're solving - and you're not alone
(got 4 V20Zs in a CoLo in Menlo Park CA that I maintain for
Genunix.Org and I visit them less than once a year at great expense -
both in terms of time and dollars)! IMHO any kind of a hardware
"hack job" and a couple of 1.8" or 2.5" SATA SSDs, combined with an
OpenSolaris plugin SATA controller, would be a better solution. But I
don't like this solution any more than I'm sure you do!
Please contact me offlist if you have any ideas and please let us know
(on the list) how this works out for you.
Regards,
--
Al Hopper Logical Approach Inc,Plano,TX a...@logical-approach.com
<mailto:a...@logical-approach.com>
Voice: 972.379.2133 Timezone: US CDT
OpenSolaris Governing Board (OGB) Member - Apr 2005 to Mar 2007
http://www.opensolaris.org/os/community/ogb/ogb_2005-2007/
I've got stacks of both v20z/v40z hardware, plus a whole raft of IBM
xSeries (/not/ System X) machines which really, really, really need an
SSD for improved I/O. At this point, I'd kill for a parallel SCSI ->
SATA adapter thingy; something that would plug into a SCA connector on
one side, and a SATA port on the other. I could at least hack together a
mounting bracket for something like that...
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
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