Status of support for 4KB disk sectors
cswiger at mac.com
Tue Jul 19 19:38:00 UTC 2011
On Jul 19, 2011, at 12:29 PM, Ivan Voras wrote:
>> Is there something in FreeBSD which is preventing you from using the drive's native DEV_BSIZE of 4096 bytes, or is it that the drive claims to have a physical block size of 512 bytes when it is really 4k?
> Nope, "only" that.
It's nice to have well-defined problems-- although it's perhaps not so nice when hardware is compelled to lie about its status because of backwards-compatibility (C/H/S vs LBA comes to mind also).
> The current state of the matter (i.e. for 9.0) is:
> * The new ATA driver has quirks for certain models of HDDs which have this false advertising (which can be manually triggered by kern.cam.ada.X.quirks=1) which causes the drive to report stripesize of 4k.
> * This information is used in gpart to size & align partitions; it will be used by the new installer
> * Default fragment size for UFS was raised to 4K so it will be aligned by default.
Excellent; thanks for the detailed reply.
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