True that!
Yes, i’ve another new disk lying on my desk, same batch though. Let me know what info you need. Just to let you know, i’ve three disks (came factory sealed, brand new) so yesterday, i just tested one and i noted all info of that drive and then i did the firmware update+sector change on second drive. So, i’ll give you all the info from the third disk!
Just to add, i did the firmware update first and then did the sector change. I did power cycle for both as well.
@winnielinnie Sorry friend, it took a little longer but i’ve collected all the info from the new drive, from the same batch:
As you can see, the capacity is different for this drive everywhere. From smartctl info, HD Sentinel, SeaTools, diskpart, Disk Management and it correctly shows 16TB aka 14902.0GB usable capacity.
Also, i was looking for some info online and i found this:
As per this info, it means that 14.55TB is the correct usable capacity. I dunno. Maybe some other users can give some insights on this before i start making the changes on every drive. I’ll wait for the answers before i jump to upgrade the firmware and change sector size.
@winnielinnie Were you able to check the SMART info you asked me to attach? Any idea?
It doesn’t seem like there’s any real negative to it. So long as these are genuine Exos, and the commands completed successfully, the numbers you’re getting might just be a calculation of overhead from 512e to 4Kn sectors.
Um, what do you mean by overhead here and why does changing the sector to 4k eats up 400GB?
This also means i’ll loose 8TB of total capacity for 16 disks of 16TB each. I’m not sure what benefit 4K sector size brings when the disadvantage is that you loose space. Also, i don’t why people said that 4K will bring 7-12% of more space ;( better reliability with wear and tear and some ECC benefits. Any insight on it @etorix @ericloewe
@winnielinnie Any thoughts on the metadata VDEV?
Changing the sector size of a hard drive from 512 to 4096 doesn’t change the RAW capacity of the drive itself. Usable space may change but only in favour of 4096 due fewer but larger sectors ie less ECC etc.
Yes, i’ve been wondering why the usable capacity shows 500GB less now. You mean the 4096 has less ECC? I’m so much confused now whether to switch to 4K or use 512e. The drives are new so i plan to do it before i setup a pool, if i have to. Can anyone explain me the benefits or the advantages of using a 4K drive instead of 512e?
From a Seagate white paper i’m quoting:
“Format efficiency gains resulting from the 4K sector structure range from 7% to 11% of a platter’s physical space. It uses the
same number of bytes for gap, sync and address mark, but increases the ECC field to 100 bytes to accommodate improved ECC
algorithms. This yields higher capacity points while also improving data integrity”
Where are you seeing this loss in space? Can you do a smartctl -a /dev/blah with one you’ve changed and one you haven’t?
Yes, of course friend:
This is brand new Seagate EXOS X16 (factory defaults, factory sealed, retail unit):
vs
Another drive from the same batch, same model, same capacity results in this:
As stated before:
After doing the firmware update and sector change to 4096, i thought to check the disk properly using SeaTools and HD Sentinel and seems like something is wrong.
Let me know if you need any other info
Can I see the full output for smartctl -a on the drive you updated please.
Changed to 4K:
512e (unchanged):
I just don’t understand why there is a loss of 500GB approx in terms of usable capacity when changing the 512e to 4K
Thats not the full output for the change drive it’s just a grep one liner.
Well, if you really need that thing to see, i can boot the system and attach. But the result is same. I did the grep as asked by the @winnielinnie
Let me know if you need the info like 512e one.
I’d like to compare the two and not just ‘User Capacity’.
Okay, sending you shortly. Please wait for me!
It seems weird on first glance that there would be a change in size going from 512e to 4kn. Might they actually be doing some weird pseudo-512n instead?
Sectors used to be 512 bytes on all disks, floppy and hard, as part of the IBM PC legacy. The increase to 4 kB and the whole 512e thing came about precisely because it allowed for better space efficiency. Strictly speaking it’s not just the ECC, though that does improve significantly (Broadly speaking, for a given level of protection, you can get away with lower density if you increase the size of the ECC-protected block) - there’s other housekeeping info like “sector ID” (which gets mapped by the disk to one (or more, for 512e) LBAs. Fewer sectors == fewer instances of such data taking up space.
The disadvantages were mostly around compatibility in the early days (systems as recent as Windows XP did not know how to boot from 4 kB sectors), with some marginal concerns about wasted space (since the smallest thing you can possibly allocate is a sector, and filesystems then put their own limitations on top of that).
Indeed. Im curious to see what ‘Sector Sizes’ reports in smartctl. Should say something like ‘LU is fully provisioned’.
Seagate EXOS 16TB (Factory firmware SN03 and factory defaults sector size 512e):
Seagate EXOS 16TB (Firmware update to SN04 from SN03 using SeaChest Bootable and sector size changed to 4096):
Ok other than changing to 4096 that only leaves us with the firmware update. It is possible that the latest firmware reserves more space than the previous one (for whatever reasons) however to test you would need to update another but not 4096 and then compare.
