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November 28, 2005

StorEdge D1000 (Again)

A D1000 is a SCSI array. Actually it is two arrays.

OK, I actually had a couple of readers who were curious about this post. What is a D1000 they wanted to know and who cares...

Well a Sun StorEdge D1000 is really just an differential SCSI array (actually two differential SCSI arrays in a single box).

It was intended for use in a rack mounted environment and could be configured as one array by crosslinking the two internal controllers. When crosslinked, you want to make sure that the individual target address do NOT overlap. Hence the comments the other day :-) The two controller cards appear as targets e and f and the disks (in a second generation D1000) would be 0, 1, 2, 3, 4, 5 and 8, 9, a, b, c, d. Note that 7 is not used because that is reserved for the host end of the SCSI connection.

The way I normally find these boxes deployed is in a boot-disk mirror. In this case the host server will have two SCSI controllers - one connected to the left hand array and one connected to the right hand array. Both arrays have their targets configured to start at zero so that the target numbers in the metadisk configuration look "similar" (i.e. less confusing for the poor sods who maintain it). For example the array I set up the other day ended up supplying c1t0, c1t1, c1t2, c1t3 and c5t1, c5t2, c5t3, c5t4. In this case c1t0 was mirrored to c5t0. Same for c1t1 and c5t1. The remaining four disks were assembled into a RAID 5 stripe.

Warning for the uninitiated - don't link the two halves together when you are connected to two controllers. SCSI is a bus architecture, not a ring technology! Use terminators instead.

Posted by Ozguru at November 28, 2005 06:00 AM


I always forget the terminators until the damm thing doesn't work, then I remember. I just don't have to rebuild it very often

Posted by: Skipjack at November 26, 2004 07:11 AM

To make matters worse the second version of the D1000 (12 slots instead of 8) which has *exactly* the *same* part number does not require a terminator (it can terminate itself). I love it when some pundit gets up and starts pontificating about the fact that "d1000s must be terminated" (or "d1000s don't need termination"). You wait until they are running at full-steam and then ask if they mean the 8 slot or 12 slot version. Instance silence (and shock).

Posted by: Ozguru at November 26, 2004 07:11 AM

you would tihnk that they would at least put a dash '12' or dash 'b' to let you know which d1000 you are dealing with.

Posted by: Skipjack at November 26, 2004 07:11 AM

They usually do. In fact there are some parts which are completely interchangeable but they give them different part numbers because they are from different servers. In this case something failed in the system and there are thousands of each model out there. The stencils are from the 12 slot model but there was a period of overlap where the 12 slot stencils appeared on the older 8 slot units.

Posted by: Ozguru at November 26, 2004 07:11 AM