SAS address for SATA disk with interposer

If you replace the physical SATA disk in a caddy that has a SAS/SATA interposer in it to make it dual-ported SAS so it can work in dual-path systems such as a Dell MD3000i does the SAS address change or is that address (similar to FC WWN) tied to the interposer?
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andyalderAsked:
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DavidPresidentCommented:
It depends.  Typically the interposers create the two WWN port IDs by XORing a subset of the NAA unique ID field of  the HDD with the two WWN port IDs in the interposer.

To answer your question specific to your system, send out the SATA IDENTIFY (hex op code EC), and get the 512-byte hex dump of the current disk and the replacement disk.  Look at the 8 bytes in offset 114h - 11Bh and see if it has all 0s.  If all 0s, for the current and new disk, the two SAS addresses will NOT change.
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DavidPresidentCommented:
But ... big danger, in the event you foolishly use a replacement disk that does not present a NAA identifier and has all zeros, you could very well get a SAS address which is a function of the bay you put the drive in..   (Some interposers do the XOR with the expander's slot identifier rather than the 2 port IDs in the interposer).

So bottom line, if the disk presents 0s in the offset 114h-11Bh, for the old & new, then the two SAS address ports will stay the same, but will typically be a function of the physical slot# the disk is in.     If the two disks have a unique NAA identifier, then the two SAS ports MAY or MAY not change, as that is a function of  the make/model of interposer.
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andyalderAuthor Commented:
This is actually a MD3000i so Dell part number PN939 for the interposer. We sent out a number of disks to the user who said they had changed them but the physical disk channel remained degraded so I was guessing that it had kept the same SAS address and therefore not noticed it was a new disk and reset the error stats accordingly..

I went to site today to look at it and the disk didn't have the interposer fitted, no wonder the second controller couldn't see it; single port SATA plugged straight into dual-port backplane.
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DavidPresidentCommented:
Pesky customers .. .can't trust them ;)
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