Exploring Advanced Format Hard Drive Technology 165
MojoKid writes "Hard drive capacities are sometimes broken down by the number of platters and the size of each. The first 1TB drives, for example, used five 200GB platters; current-generation 1TB drives use two 500GB platters. These values, however, only refer to the accessible storage capacity, not the total size of the platter itself. Invisible to the end-user, additional capacity is used to store positional information and for ECC. The latest Advanced Format hard drive technology changes a hard drive's sector size from 512 bytes to 4096 bytes. This allows the ECC data to be stored more efficiently. Advanced Format drives emulate a 512 byte sector size, to keep backwards compatibility intact, by mapping eight logical 512 byte sectors to a single physical sector. Unfortunately, this creates a problem for Windows XP users. The good news is, Western Digital has already solved the problem and HotHardware offers some insight into the technology and how it performs."
Re:Large sector size good? (Score:1, Insightful)
If you read the article carefully, the new size is only 4K, not 4096K. The 4K size actually matches very well with most common files ystems. The 4096K is an error in the article.
Re:Defrag (Score:1, Insightful)
Use a filesystem that only fragments when there is not enough contiguous free space to write a given file and you won't need to defrag.
Re:Large sector size good? (Score:3, Insightful)
You want the sector size to be smaller than the average file size or you're going to waste a lot of space. If your average file size is large, and writes are sequential, you want the largest possible sector sizes.
Re:Large sector size good? (Score:5, Insightful)
The filesystem's minimum allocation unit size doesn't necessarily need to have a strong relationship with the physical sector size. Some filesystems don't have the behavior of rounding up the consumed space for small files because they will store multiple small files inside a single allocation unit. (IIRC, Reiser is such an FS.)
Also, we are actually talking about 4 kilobyte sectors. TFS refers to it as 4096k, which would be a 4 megabyte sector. (Which is wildly wrong.) So, worst case for your example of a thousand 1k files is actually 4 megabytes, not 4 gigabytes as you suggest. And, really, if my 2 terabyte drive gets an extra 11% from the more efficient ECC with the 4k sectors, that gives me a free 220000 megabytes, which pretty adequately compensates for the 3 MB I theoretically lose in a worst case filesystem from your example thousand files.
Re:512x4=4MB?? (Score:5, Insightful)
No. Just no.
Never use the term 'KiB' for kiloBYTES ever again. Just don't do it. I don't CARE if it's "the new standard". Screw that, it's KB KiloBytes.
This "new" standard mandated by the IEC can eat me.
1024 bytes IS, and forever will be, 1 KiloByte (KB)
1000 bits IS, and forever will be, 1 KiloBit (Kb)
1999 and the IEC can DROP DEAD. I will never. EVER. Use the new """""""""""""standard"""""""""""".
That said, excellent job highlighting the dreadful editing, inaccuracies like that are so confusing to try and keep straight between what is written and what was MEANT. Thumps up for you!
Re:Defrag (Score:1, Insightful)
Use a filesystem that doesn't fragment unless absolutely necessary, and it's extremely likely you will never notice a fragmentation related performance issue.
Free disk space: 1.21 Giblets (Score:5, Insightful)
"it's 4 KiB or just 4096 bytes."
No. Just no.
Never use the term 'KiB' for kiloBYTES ever again.
"kiB" is for kibibytes, not kilobytes...
The introduction of those new units always kind of grated me, as it went against all the 20-odd years of experience I'd had with computers up to that point. But, I have to say, "kilobytes" and "megabytes" and "gigabytes" had always been ambiguously defined. Usually RAM would use the power-of-two definitions and disks would use the power-of-ten definitions... As someone who appreciates precise language, I think this effort to disambiguate the terminology is a good thing, even if it goes against what I learned about computers as a kid. I don't think making the opposite change (i.e. keeping "kilobyte" = 1024 bytes and making a new term for 1000 bytes) would have made any sense at all - the "kilo" in "kilobyte" goes against the normal definition of "kilo". I think it was always kind of sleazy that hard drive manufacturers could tell you they were giving you a megabyte of storage and it would be less than what the computer considers a "megabyte" - but the prefix has a definition that predates its use in computing, and from that perspective I think that usage, while problematic and misleading, was legitimate.
Re:Marketing lies (Score:3, Insightful)
And that kibi/gibi stuff only means that we have given up fighting and submitted to those marketing lies
Or maybe it just means that programmers have finally figured out the metric system?
In EVERY other discipline out there kilo means 1000. The reason it was defined as 1024 in IT wasn't out of some kind of brilliance, but rather shear laziness. Yes, I understand binary, and yes I understand why binary units are useful. So does the SI, which is why they invented the kibi prefix.
I could care less about marketers one way or another. I do care that a storage medium that stores one 1 MB per cm^2 does not store 10GB per m^2 if you use IT lingo. I don't see how that is in any way convenient for any engineer who actually works with anything in the physical world.