EMC 520 sectors reformat to 512

First the answer is "it depends".  I've changed the sectoring on several EMC branded drives. I've failed on others.  It comes down to whether or not the firmware accepts the command(s).  

But just for sake of argument, let's say the HDD allows you to do this.  One still has to reprogram the bad block layout, and go through media init, and reconstruct them.   Disks report that they have X blocks, not that they have X Bytes.  So the number of blocks will change.  Unreadable data at block X is going to get moved to block Y once these change.  If this is a secure drive (SED / TCG / FIPS) then it is going to be password protected too, so until you get past that then it wouldn't matter even if you could change block size.  The security would prevent you from reading or writing to it.

So here is the deal .. get your money back if you can.  You're not going to find anything for free out there.  You'd have to ship one of the disks to somebody who has the software to change the block size, and then make the necessary formatting/capacity bad block adjustments or your disk won't do bad block error remapping properly. -- resulting in data loss.

You'd have to then eat shipping expenses to get the disk to somebody and pay for their time, and no way to know if the disk will allow the change until it is actually tried.  If the drive allows it, then the 4TB drive is going to have to be hooked up to a test bench about 24 hours to reformat and media scan, so it ties up equipment.

They money and time involved to do this particular change is probably going to be more than it costs you to buy 4 used 4T SAS drives on ebay that are already formatted and tested for errors.
Sorry

http://sg.danny.cz/sg/sg3_utils.html has a sg_format command but as dlethe says it depends on whether the drive will obey it and also you would need to connect the drives to a SAS HBA, you can't send raw commands to the disk through a PERC RAID controller.

I discovered last night that i would need a different raid controller late last night, looking into that. But yeah it's probably 50/50 on getting the thing to work for me. Thank you for your time and the process id likely need. I'll update once i have a raid card. Going to try that and see what happens.

Not a RAID card, a dumb SAS HBA,

Ah, ok thanks. That then.

So you're going to spend a few hundred dollars on a SAS JBOD controller (hint ,buy a used one for $50 on ebay) that is guaranteed not to work on the drives as they stand now??

The sg_format is only part of the process.  You can send any raw command(s) you want with the sg_tools. The trick is knowing what to do about the bad block table. You have to run through combinations to get it right or bad blocks won't work right.  Drive could end up in degraded mode which means sending another command and waiting 8-12 hours till you can try another combination.  EMC firmware uses manufacturer-specific layout.  Then to make disks with EMC firmware work properly, you have to reprogram some settings on mode page 1, 8, 1A, and 1C at a minimum.  (I know that from experience)

Depending on the model of disk and subsystem it came from, they will carve out a reserved area. They do this so disks format to a constant size so they can substitute different disks but they will all report same number of blocks.  That way they can substitute different disks that would ordinarily differ in capacity, so they'll all be compatible with existing RAID volumes.  That is one more step to consider, you probably want to reprogram capacity to get 100% of the disk.  The reserved area won't go away by changing block sizes, but the location will change because the block count is going to change automatically.

If these disks had stock non-vendor-specific firmware, then no big deal, sg tools would be fine.  But EMC firmware is different.

To be blunt, you're spending good money after bad money.  You won't find a controller that will let you use the disks in 520 mode. I failed to mention before that unless these were boxed never-before-used drives then you're inheriting drives that may be in horrible shape with bad block tables nearly full and/or full of non recoverable media errors.  

Such is the risk of buying any used disk drives.  No way did anybody run any diagnostics on those drives to assess their health or even look at the log page counters because that sort of code that works with 520B drives with EMC firmware just isn't something you're going to find.

You have 4 used disk drives in unknown condition,  that you have to buy a special controller for, that have to be sent to somebody who has the code and experience to know how to reprogram the drives; you have to pay to ship them;  you have to pay to convert them; conversion and reformatting takes around 24 hours each so you pay extra if for no other reason they tie up the test bench for 4 calendar days total; and there is no guarantee this firmware will allow them to be reprogrammed.

Look, I have everything I need to convert the disks and even I wouldn't buy four USED disk drives that i might not be able to convert that may be full of media errors.

Dude, cut your losses.  (P.S. No i am not trying to get you to pay money to me to convert them. It is a pain to do this, and I'd charge you more than what you paid for the drives in the first place .. anybody who was capable of doing this would too.  Changing block size is just a part of what has to be done to drives with EMC firmware)

Sorry