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Re: Support for 4KB sectors size disk ?
On Jan 11, 2010, at 9:55 PM, Johnny Billquist wrote:
> Thor Lancelot Simon wrote:
>> On Mon, Jan 11, 2010 at 05:21:41PM -0800, John Nemeth wrote:
>>> Although at one time it was common to be able to format drives
>>> with different sector sizes, that was over two decades ago. It is
>>> doubtful that any current operating system would be happy with a hard
>>> drive that had a sector size other than 512 bytes. Thus they can't
>>> change that until current OSes become an historical footnote.
>> You're kidding, right? Maybe, again, you should stop speaking whereof
>> you know not.
>> Just as one example (which accounts for the large number of SCSI/FC/SAS
>> disk drives one still finds on the surplus market which are formatted for
>> 524 byte sectors):
>> It may not be an operating system you use, but it's certainly still a
>> current one.
> Well, technically any disk will have more than 512 bytes of data for each
> sector. It's just that 512 bytes is what is presented to (and usable by) the
> host system, and those disks by IBM are no different.
> They still present 512 byte sectors to the host OS. To quote the page you
> linked to: "The data portion of the sector remains at 512-bytes for all host
> What underlying format is used, and what data the controller stores and uses,
> to make sure the host is serviced with the correct, and fault free data, is
> of little concern here. We are not, after all, making disk controllers, are
> However, the age of random block sizes for disks (exposed to the OS) is way
> more than 2 decades back.
> I'd say that would be about 4 decades ago, and maybe more.
The IBM 360 series, and its flagship operating system OS/360, circa 1965, made
heavy use of such features. IBM introduced its first 512-byte sector drives
around 1979 or 1980, but they certainly didn't abandon the older style then. I
stopped working on mainframes some time in 1981, so I don't know what happened
> Oh, and I don't expect the 512 bytes/block paradigm to change any time soon.
> It's probably one of those things we will live with for ever. The underlying
> disks might start doing something else, but you'll probably still be able to
> see, and treat the disk as if it had 512 byte blocks for as long as we live.
> Just my two cents...
> Johnny Billquist || "I'm on a bus
> || on a psychedelic trip
> email: bqt%softjar.se@localhost || Reading murder books
> pdp is alive! || tryin' to stay hip" - B. Idol
--Steve Bellovin, http://www.cs.columbia.edu/~smb
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