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Exploring Advanced Format Hard Drive Technology
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."
You mean 4096 bytes, not 4096k, right? Last time I checked, eight 512 byte sectors is considerably smaller than 4MB.
Guys, filesystem block/cluster size is not the same as hard drive sector size.
Jesus.
If Advanced Format drives were true 4k drives (i.e. they didn't lie to the OS and claim they were 512 byte drives), they'd work great on Linux (and not at all on XP). Since they lie, Linux tools will have to be updated to assume the drive lies and default to 4k alignment. Anyway, you can already use manual/advanced settings in most Linux parititioning tools to manually work around the issue.
No, that's totally wrong. The drive may well use 10 magnetic "cells" to store a byte (e.g. with 8b10b modulation or something similar), but that's an implementation detail. As far as everything else is concerned, bytes are 8 bits.
Depends on the drive. In recent electrical signalling (Gb ethernet, SATA/SAS, etc.) the 8b10b encoding scheme has been very popular; and is 10 bits to a byte. The extra bits are for recovering the clock signal. The HDD has to do the same, but the manufacturers don't have to adhere to any standards inside their case.
Now, if you're asking the question "how many bytes in a MB?" there is great debate. (The answer is, and has been from the first RAMAC*, 1,000,000. However, the binary bus people like to argue otherwise; and Microsoft Windows is one of the protagonists.)
* Okay, so technically the RAMAC was 5,000,000 words, where a word was 7 bits.
But as I understand it, byte == octet on all hardware that 1. allows the general public to develop applications and 2. is not discontinued.
Anandtech has a much better write up on this technology, complete with correct conversions from bits to bytes, knowledge of the difference between 4096 bytes and 4096 kilobytes, and no in-text ads.
IBM's GPFS is one, though it ain't free it does support Linux and Windows both mounting the same file system at the same time. They reckon the optimum block size for the file system is 1MB. I am not convinced of that myself, but always give my GPFS file systems 1MB block sizes.
Then there is XFS that for small files will put the data in with the metadata to save space. However unless you have millions of files forget about it. With modern drive sizes the loss of space is not important. If you have millions of files stop using the file system as a database.
Linux has had 4096 block size in the kernel for ages. See this article The issue being, as I recall somebody say, is that fdisk cannot properly do this. So use parted and you will be ok. ext3 and jfs and I suppose xfs and a whole bunch of others support the 4096 block size as well. BTW, who "tackled the XP issue pretty quick"? was it Microsoft or was it the hard drive makers. AFAIK a few hard drive manufacturers are emulating a 512 block size so it is not a complete fix.
Society use your Sciences
This is especially important for all you who manage a SAN. Learn it, love it, live it.
To learn why disk partition alignment can be important, please reference the following blog post: http://clariionblogs.blogspot.com/2008/02/disk-alignment.html
Instructions for Stripe Alignment/Partition Alignment within a Windows Operating Systems
Reference the following link for info on DiskPart, http://support.microsoft.com/kb/300415
1 - At a command prompt on a windows host type diskpart
2 -Type select disk X (X being the numbered disk within disk management that you want to align)
3 -Type create partition primary align=64
4 -You can then format the drive and assign a drive letter to it
Be careful, tzanger, I think Mr. Grumbine may be bating you!