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On Tue, 9 Mar 2010, Rob Beard wrote:
I'm a bit confused about all this, how I understand it from reading the BBC article, there is space between the 512 byte sectors which is wasted?
Yes. Each sector on the disk has a header, then the data, then the trailer which includes ECC information. These headers are a number of bytes long - maybe even 10's of bytes. The header is used by the drive firmware to tell it where the sector starts, and the trailer to tell it where it ends - or to make sure it's ending at the right place. Then there is ECC data used to correct any "soft" errors read by the drive.
If you make the sectors bigger (8 times bigger), then this information is only written to the disk once per every 8 sectors. So overall you save space. Same number of bits on the drive, but less of them are used to identify stuff on the drive.
I'm just wondering with this fancy new 4K sectors, does that mean we're not going to loose as much space as we do at the moment?
It has nothing to do with losing space to the operating system - which I think is what you mean here. Both Linux and Win need space to store the filesystem information and Linux reserves 5% of the overall capacity for emergency use too. (And efficiency - at least under ext2/3)
What I mean is, for instance, my new 320GB hard drive has a formatted capacity of about 297GB (or is it GiB?). I gather this is because the drive is 320,000,000,000 bytes rather than 343,597,383,680 bytes. So I'm wondering, does this mean we'll start to get the extra 23GB back on a 320GB drive?
The drive capacity in terms of number of usable bytes it can tore will be larger, but the OS will still use a portion of it for it's own use.
And MB vs MiB ... Ah, that's drive salesmen for you. 1MB in drive numbers is 1,000,000. 1MB in computer numbers is 2^20 = 1048576. To avoid confusion, in 2000 the term MiB was coined to represent powers of 2, but the drive makers stuck with decimal.
So because we're conditiond to working in KB, MB, etc. we think the drive is bigger than it really is. Clever disk sales people.... They'll just take a 1.5TB drive and call it a 2TB drive - we'll see the capacity go from 1.1TiB to 1.5TiB (for example)
So big win for the drive makers - no hardware changes at all, just a firmware change yet the drive capacity is increased, so the price can be increased too.
Good to see it's supported in Linux anyway, and I guess XP users will just see a bit of a performance hit.
Quite a bit according to the tests, but not hard to put right. Gordon -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html