I ranted about this on Twitter a few days ago when we discovered it the hard way but I want to write it down here and then cover why what Intel did is a terrible idea. The simple and short version is this:

Intel switched one of their 'datacenter' SSDs from reporting 512 byte 'physical sectors' to reporting 4096 byte physical sectors in a firmware update.

Specifically, we have the Intel DC S3500 80 GB model in firmware versions D2010355 (512b sectors) and D2010370 (4K sectors). Nothing in the part labeling changed other than the firmware version. Some investigation since our initial discovery has turned up that the 0370 firmware apparently supports both sector sizes and is theoretically switchable between them, and this apparently applies to both the SC3500 and SC3700 series SSDs.

This is a really terrible idea that should never have passed even a basic smell test in a product that is theoretically aimed at 'datacenter' server operations. There are applications where 512b drives and 4K drives are not compatible; for example, in some ZFS pools you can't replace a 512b SSD with a 4K SSD. Creating incompatible drives with the same detailed part number is something that irritates system administrators a great deal and of course it completely ruins the day of people who are trying to have and maintain a spares pool.

This Intel decision is especially asinine because the 'physical sector size' that these SSDs are reporting is essentially arbitrary (as we see here, it is apparently firmware-settable). The actual flash memory itself is clumped together in much larger units in ways that are not well represented by 'physical sector size', which is one reason that all SSDs report whatever number is convenient here.

There may well be good reason to make SSDs report as 4k sector drives instead of 512b drives; if nothing else it is a small bit closer to reality. But having started out with the DC S3500 series reporting 512b sectors Intel should have kept them that way in their out of box state (and made available a utility to switch them to 4k). If Intel felt it absolutely had to change that for some unfathomable reason, it should have at least changed the detailed part number when it updated the firmware; then people maintaining a spares stock would at least have some sign that something was up.

(Hopefully other SSD vendors are not going to get it into their heads to do something this irritating and stupid.)

In related news we now have a number of OmniOS fileservers which we literally have no direct spare system disks for, because their current system SSDs are the 0355 firmware ones.

(Yes, we are working on fixing that situation.)