[Freedos-user] Re : Support for 4k byte sectors

[Bertho G. <y31...@ya...>]

Replying to Eric Auer <e.auer@***.de>
 
> This refers to the following quote from an earlier 4 kB
> related mail:
 
>> I stumbled upon a couple pages that say otherwise : "the industry"
>> has agreed to sell AF disks only *until the end of 2014*!
 
> It was actually you yourself who said that on 25 Jan 2012
> ;-)


I can't deny I wrote the above - in my haste I omitted the all important "e" as in "AF512-e".  What the hard disk industry has agreed to, reportedly, is that they won't put disks without 512-byte-sector emulation on the market before 2015. On the other hand, almost all manufacturers have already switched their processes to produce hard disks with /physical/ 4096 b/sectors. Hitashi is the only important one who has not yet completely converted, I hear.

A contrario, they are free to remove the /emulation/ from the firmwares of disks sold starting January, 2015. What they /won't/ be doing is reverting to 512 bytes per sector, that game is over.

> AF = Advanced Format = 4096 byte per sector, i.e.
> "Advanced"
> meaning "if you find 512 byte better, you are not modern"
> :-p
 
> Also, "advanced" format lets more data share less ECC error
> correction data, squeezing out a tiny bit of extra capacity
> and a bit of extra resistance to data errors...

(skipping MSWindows relative alignment and other considerations )

>> Manufacturers have no interest to reverting to 512
> bytes sectors - 
>> since 4K sects allows them to advertise higher
> capacities
 
> No. As Tom said, large sectors are only a workaround for
> WinXP
> and similar "MBR partitioned" operating systems. 

No, the disk indusctry had been pushing larger sectors for years and it was MS putting  the brake until it was ready to deal with them. 

>With GPT, you have no relevant limit to the number of sectors any more
> and sectors can be small again :-)

Yes with GPT (or a revision of MBR with wider sector numbers) they /could/ be small again, but that isn't going to happen.

4K sectors (and possibly larger) are here to remain. Well, until mechanical  hard disks disappear.


> On the other hand, everything is pretty virtual today
> anyway,
> and SSD / flash have better performance with access in
> larger
> blocks, but that does not mean that block has to equal
> sector.
> It could also equal cluster and FORMAT already supports
> making
> clusters of 4 kB or bigger align with 4 kB boundaries...
> ;-)
> 
> The "virtuality" will also mean that you eventually have to
> load a "PC BIOS interrupts" legacy API module for EFI
> BIOSes.
> Luckily those also exist as open source, if vendors get
> lazy.

UEFI is another can of worms (and Intel's implementation is huge and buggy) altogether... Everything is possible but /optional/ and I wouldn't bet PC vendors in general will include the BIOS module in future EFI PCs. No BIOS -> no DOS! unless the kernel is deeply revised. 

> PS: As you say you read this on freedos-kernel, but are only
> on
> freedos-user (where you mailed) I took the freedom to CC
> both.

Thanks

-- 
Czerno