Summary - Purchasing Information E280R & A1000

Wow thanks to all that replied I really appreciate
your comments.  At first I was just as confused as I
was before I asked the question, because I was getting
both answers on sharing the A1000 between 2 machines. 
One thing was clear however I will contact
http://www.sharkrack.com for my rack.  This morning on
the drive in, I decided to play it safe and go with
the one machine to the A1000, then I read the replies
that came in over night and now I feel strongly that
is the answer.  However, Now I'm think I need to look
into a D1000, it might truly be what we wanted all
along.

All of the replies I received are below with my
original question.  Thanks to everyone again.  Coming
from the dreaded IBM VM mainframe world I still have a
whole lot to learn and this list sure makes my life
much easier.  Oh a few mentioned asking my sales rep,
I would have to say I didn't know such a thing existed
and that is probably because we are so small that we
don't look very interesting to sales reps.  Some
suggested a T3, and we knew about them, but just
couldn't afford it, but thanks anyhow.

Original Question
Hi Admins I'm sure this is a newbie question but I
sure need your help, so please forgive me, I just
don't know anywhere else I can get the correct
information. We are thinking about buying an E280R and
an A1000 and in talking to different vendors I've been
given conflicting information. The A1000 comes with 2
"Differential UltraSCSI to host ports" 

One vendor indicated that I could connect one of the
Differential UltraSCSI to the E280R and one to my E25O
and share the Hard Drives on the A1000 between them.
Or I could connect both Differential UltraSCSI to the
E280R and have two paths to the same box. (this is
what I'm hoping is correct) 

The second vendor indicated that the E280R could only
use one of the Differential UltraSCSI ports and the
A1000 could not share the hard drives with another
box. This same vendor said the second port was for a
tape drive or some other device type. 

The other clarification I need is I wanted both
devices (E280R and the A1000) to be rack mounted, and
a vendor indicated that Sun Storage A1000 rackmount
kits were only for Sun racks. Is this true? I had
assumed I could order a Rack from anywhere. 

Answers or replies

>From Tony Walsh <Tony.Walsh@Sun.COM
I'm sure you don't want to know this, but here is the
answer. (I do these installations quite often) The
A1000 comes with 2 SCSI connectors which when attached
to a single host are for one 'in' port and one 'out'
port. The only time a single A1000 array can be
attached to 2 hosts is in a cluster configuration and
only with the cluster failover software in place. The
confusion over the one vs two host ports issue is
likely to be caused by the fact that the A1000 array
and the D1000 array are documented in the same
Installation Guide. The A1000 is a hardware RAID array
and the D1000 is JBOD (Just a Bunch Of Disks), and the
only physical difference between them is the
controller board. 

If your intention is to cluster the E280R and E250,
and not forgoing the fact that the combination may or
may not be recommended at all, then you may be able to
attach one A1000 to your two hosts. 

The second port on the A1000 is NOT intended for any
device other than another A1000 in that you can chain
two A1000 arrays together (and more are possible but
not necessarily recommended). This is because the
RM6.22 software which you have to install with the
array gets very confused if there are devices on the
same host controller (as in c1t5d0) that are not under
its control. 

As for rackmounting, the E280R should be fairly
straight forward, as the mount points are designed to
fit a standard 19 in rack as long as it is at least
700 mm deep (I recommend an 800 mm depth). The A1000
rack mount kit however, comes with two side rails
which are attached to Sun racks via internal vertical
rail attachment points. These vertical rails are not
normally found in standard 19 in racks at the correct
position to be useful. The other portion of the rack
mount kit for an A1000 is a light sheet metal shell
that goes around the array. This is designed to fit
neatly into the 2 side rails mentioned above but the
array can just as easily be supported by a tray in the
19 in rack. In this way the metal shell can be used to
prevent the array from moving on the tray by securing
the front of the shell to the standard 19 in mount
points. Regards Tony Walsh 

>From Jason Grove <jgrove@wvu.edu> 
I have a A1000, and from my experience you can not
connect two machines to it.. Only one.. It is sort of
like a regular scsi device, the other port is for
chaining something else to it (I tried dual connecting
it to a host and that did not work. And you MUST have
a terminator on the other port if nothing else is
plugged in to it)... 

I had to buy an Ultra SCSI card (LVD I believe, it has
2 VHDCI connectors on it) for it to use on my E420R...


Also for the rack mounting, It will not fit in a
standard 19" rack (or at least I could not find the
way..) When we bought it Sun told us it is a Desk top
unit.... You would need a 24" rack with a "table" to
support it inside of a rack. That is why we are
starting to get T3's since I can rack them. If you do
find a way to rack it, I would be intrested in hearing
it, cause I believe it is about 1/2 inch to big to fit
in the rack. jason 

>From William Hathaway <wdh@ftope.com
the A1000 has 2 SCSI connectors, but only 1
controller. The disks in the A1000 can only be
accessed by a single host at a time. The two
connectors allow the A1000 to be used in HA type
situations where you have one active and one standby
host. Sun makes things pretty confusing because they
combine the literature for the A1000 and D1000. 

I know sharkrack.com has rack mount kits for the A/D
1000, but haven't used them. Good luck, /wdh 

>From JULIAN 
Sun documentation with an A1000 explain how to connect
it to two servers and share the device. Shared disks
would have to be mounted read-only otherwise two
systems writing to the same drive could cause
corruption. The sun rack mounts are intended to fit
longer than standard racks but can be made to fit
other racks with drilling of two holes and mounting
the tail bracket backwords. 

>From Fletcher 
You can dual host the A1000. You only need to change
the scsi initiator id on one of the boxes and it will
work fine. Cheers Joe 

>From Frank_DeMontier@ssga.com 
I have E220R's and D1000's that share drives, I
believe the second vendor is incorrect...unless there
is nuance with the A1000 architecture... Also, I
believe the A1000 rackmount kit will only fit a Sun
Storage rack....unless you do some major alterations
to an existing cabinet. Good luck! 

>From Matthew Stier 
The A1000/D1000 rackmount kits are intended for Sun's
racks. They have fixed mounting holes, and you will
need to adjust your racks to match Sun's spacing. I
have A1000's and D1000's and I simply drop them on the
medium weight shelves for the racking system I use. 

>From John Martinez <john@mtbiker.net> |
You cannot share an A1000 amongst two servers. The
A1000 is a single channel SCSI array. You could use
the D1000, which has dual channels, but it doesn't
have hardware RAID capabilities. You should also check
out the T3, which is a RAID array in a Fibre Channel
format. 

>From Patrick Shannon <pshannon@macromedia.com
The SCSI on the A1000 is indeed differential. I don't
know about the 280, but all other Sun servers do not
come with on board differential scsi host adapters.
You generally need to add one. The PCI, dual
differential card from Sun is popular and gives you
enough slots for two A1000s should you have them. 

The A1000 does have two diff scsi ports, but one is
terminated generally and the other goes to the host. I
have never seen one deployed as a part of a daisy
chain. I do not think you can share drives between
hosts using the A1000. The 5200 is the only Sun disk
array that might be a good bet for that. Partially
because it is a Fibre Channel based system which can
easily be attached to multiple hosts. In any case, you
will need special clustering software to support a
multi-homed disk and quite a bit of planning and
testing to get it working. Patrick 


>From Pankaj Anand
I think storage can be connected to both the hosts but
scsi initiator-ID has to be changed from 7 on one of
the host to avoid conflicting. But I haven't seen
anybody sharing A1000 storage. Other solution of
connecting both the channels to the hosts is very
practical and is being used .. Secondly the racks
should be standard racks and these servers can be
fitted into any standard racks. ...........Pankaj 

>From Frank Smith <fsmith@hoovers.com> 
Yes, the A1000 rack mount kits are only for Sun racks.
It's just a non-adjustable shelf (no slides), so any
kind of shelf that fits in your rack will work just
fine. I believe that the 12-disk backplane is split in
the middle to provide two 6-disk SCSI busses. You can
either use it as two 6-drive chains or bridge it into
one 12-drive chain. I don't think you can share a
12-drive set between two machines, but I could be
wrong. Best bet is to check with you Sun rep for
clarification. 

>From Harrington 
I am not familiar with the E280R, but I suspect you
may need to purchase a card (or cards) to insert in
the E280 to connect the second USCSI cable to the
A1000. But you should be able to wind up with what you
want (two connections to the E280 from the A1000).
The vendor who says you can share the drives between
two CPU's is probably saying (for example) droves 0-2
in the A1000 can connect to the E250, and drives 3-5
can connect to the E280. I still have not heard of any
ability to connect one drive to two separate machines,
where both machines control the drive at the same
time.
Regarding the A1000 in a non-Sun cabinet, I can not
imagine a problem. If worst comes to worst, put a
shelf in the (non-Sun) cabinet, and put the A1000 on
the shelf. I did something similar to that when I was
in VA DEQ. 
Have you talked to the SUN guys down in Cary, NC?
Danny Berrier, the techie, is quite helpful. 

>From : bergman@panix.com 
Yep. You'll have two paths to the same box, but you'll
need to configure that within software. The A1000
won't prevent you from doing something bad, like
accessing the same partition via different controller
channels. It's up to the OS to deal with that. 

Run away from the second vendor--fast! Sure, you could
daisy chain an A1000 to another SCSI device, such as a
tape drive, but the most common use is probably to
dual connect a single A1000 enclosure to two servers,
as in a cluster. 

If your racks can take shelves, you can put an A1000
on one of those. If not, and you must have the
rackmount version, get the "data center" flavor of
A1000 from Sun, as opposed to the (tabletop)
"workgroup" version. I'm not sure, but I believe that
an A1000 with the mounting kit will fit in any
standard rack (unlike some Sun products--the 3500 for
example, or the E450--that require surgery or special
racks. Mark 

>From Mike <mmmmm@connectnet.com
We have many D1000's in Chatsworth MegaFrame 19in
cabinets. The kits that come with the A1000 or D1000
are for Sun cabinets only, but you can definitely put
your arrays into a standard rack using a different
rack kit. We use kits from http://www.sharkrack.com
These kits require absolutely no extra space above or
below the array for mounting. I do not have a
definitive answer for your other questions. Good luck,
Mike 

>From : Darren Dunham <ddunham@taos.com> 

It's a single scsi bus. You have both ends. You should
terminate one side if it is only attached to one host.


You could probably do that, but I don't know that
having two paths to the same host will get you
anything. The drives inside only have one path. If you
lose the bus, you'll lose both sides of it. 

It's a scsi bus. Properly configured, you can attach
it to two hosts. It's no more magical than a
differential scsi tape drive. 

The rack kits only fit a sun rack. You can order a
rack from anywhere, but it will be different. Most
Telco/datacenter racks have mount points parallel to
the front/rear of the machines. Sun racks have mount
points parallel to the sides of the machines. The
racks fit in this second orientation. Whenever I've
placed A1000s in telco racks, I've used shelves and
some bracing like cables or straps. I've never used an
A1000 rack kit. 

>From Christopher Ciborowski 
Let's debunk these 1 by 1: The A1000 has 2
differential SCSI ports, 1 in and 1 out. You can
connect a server to the in port, and daisy-chain
additional diff SCSI devices off the out port. You
cannot connect both ports on the Diff SCSI hba to the
same array. It will not work, unless you change the
SCSI initiator id for 1 of the 2 controllers on the
Diff SCSI hba, but then you still have an issue with
multiple paths to the same disk (which is more of an
admin issue). I guarantee that Sun will not support
this config. You can connect 2 servers to the A1000,
one on each port (E280R on port 1 and E250 on port 2),
however, Sun only supports this in a cluster
configuration, as both servers can see all of this
disks. To prevent the servers from accessing the data
at the same time, the cluster framework with volume
manager manages the "ownership" of the disks at any
given time. Both the E280R and A1000 are rack
mountable, but, they are rackmountable in Sun
(enterprise expansion cabinet) and standard 4 post
racks which you would see in a data center holding NT
gear. Teclcom racks (19") that have 2 posts require
you to shelf the server and array. -Chris 

>From dana@dtn.com 
I don't know about E280's, but A1000's can be hooked
up both ways. Dan 

>From Jed Dobson 
You can only do a single attach. Think of it as an In
and Out port. You can daisy chain A1000's but not
dual-port them. If you want to mess with dual
initiator SCSI (you don't) you can attach to two but
they will share a bus in this case, not really a good
idea. The SG-ARY155A-72R4 for example will mount in a
standard 19" rack. Some models will only mount in a
Sun rack. In the description it will be A1000
rackmountable the Sun rack only model is a -GR5. You
want -R4. -jed 

>From Jon <jon@slurpee.org> 
I know that you can share drives on the d1000, but I
dont think that that is available on the a1000 without
a controller upgrade (on the a1000, not the 280). Let
me know if I'm wrong :) Thanks, jon 



=====
Kathy Ange
Virginia Department of Agriculture & Consumer Services
Information Systems
(804) 786-1340 Voice Mail
(804) 786-2110 FAX

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