[syslinux] Advanced Format Technology

[H. Peter Anvin]

On 06/15/2010 03:58 PM, Gene Cumm wrote:
> While researching another issue unrelated to Syslinux, I found some
> mildly disturbing news that affects Syslinux.  As HPA stated back on
> 2009-06-04, hard drive manufacturers are pushing towards a 4096B
> (4kiB; 4k) native sector size.  They're calling it "Advanced Format
> Technology".  It appears that WD (Western Digital; WDC) is the first
> with some products being released back in December and that Seagate
> just recently "jumped on the bandwagon".
> 
> Seeing as HPA's mention of the 4kiB sector back on 2009-06-04 was the
> only mention I've seen and "Advanced Format" can't be seen anywhere in
> the list archives, I felt it worthwhile to mention "it's here", at
> least to some extent.
> 
> In WD's whitepaper (PDF available by selecting language at
> http://www.wdc.com/wdproducts/library/?id=216&type=87), it does,
> however, talk about performing in-drive emulation from 512B to 4096B
> sectors and that they have a utility
> (http://www.wdc.com/en/products/advancedformat/) to "realign" for
> "performance" (still can't be certain what this really means;
> sacrifice 1/64 capacity by packing (63) 512B sectors on (8) 4096B
> sectors?).
> 
> Has this been discussed at all off-list (ie IRC)?  With the in-drive
> emulation, it seems like it either won't affect anything or it won't
> affect it for now.
> 

Logical sector size (as opposed to physcial sector size) is likely to
remain at 512 for at least some time.  "Advanced Format" is, ahem, at
the very best a euphemism.

Realigning for performance just means changing the partitions to all be
on 4K boundaries, which is a good thing; for FAT it might also pad some
of the internal data structures to make sure the clusters are also aligned.

	-hpa