Advanced Format Hard Drive setup question

[nukedathlonman]

Just an odd question about the new 512e (4K sector size drive with 512 byte emulation) hard drives on the market. I just upgraded my hard drive in my trusty notebook because I ran out of space, and all I could get was one of these new drives 4k sector sized drive - a Western Digital Scorpio Black WD5000BPKT (old drive was a Scorpio Black WD2500BEKT). Took me a few tries to get everything transferred over (problems with the transfer of the Windows & the hidden recovery partition's), and everything is running great as of this time. I see a huge performance boost across the board with the drive in both Vista and Linux. However, I have come across one odd thing. The WD Alignment tool shows my Linux root partition to be out of alignment, but I'm not seeing any of the signs or symptoms of a miss-aligned partition. Should I be worried about this or not? I suspect it's in alignment else I'd see a huge performance penalty which I'm not seeing...

[GreyGeek]

Re: Advanced Format Hard Drive setup question

I suspect that you may run into problems as the disk fills up.

Your answer is here, but I am copying the whole article in this thread because they have a tendency to disappear.

Linux

Linux as an operating system is a combination of a kernel, user space utilities and customized packaging provided within the "distributions" such as Ubuntu, SuSE and Redhat.

The Linux kernel has had specific support for the alternate sector sizes and offsets used by WD Advanced Format disk drives since version 2.6.31. However, distributions based on Linux 2.6.34, the latest stable version of Linux, will provide the most thorough support. Advanced Format parameters are available in the sysfs file system from this kernel version onwards. Kernel versions older than 2.6.31 will not specifically detect Advanced Format Drives, but with proper alignment the system performance will be maintained. To ensure the best performance, it is important to:

* Align partitions to the internal 4KB sector boundaries of the drive.
* Make sure that data writes are aligned to 4KB sector boundaries.

Partitions are created by a number of possible utilities under Linux with "fdisk" and "parted" being typical command line tools. Parted is one of the better tools and from version 2.1 onwards it includes support for aligning Advanced Format drives. Fdisk and earlier versions of Parted won't automatically align partitions but can be used manually to set up the correct partition boundaries.

The Linux partition editor: parted, has an alignment option to ensure that Advanced Format drives are correctly configured from version 2.1:

-a alignment-type, --align alignment-type

valid alignment types are:

none Aligns to 512 byte sector boundaries.

cylinder Align partitions to cylinders.

minimal Use minimum alignment: 4KB on AF drives

optimal Use optimum alignment: 1MB boundaries

The default from parted 2.2 is to align to 1MB boundaries - optimal. Use minimal or optimal for Advanced Format drives. For example if your drive is sda:

parted -a optimal /dev/sda

will ensure that parted creates partitions on 1 MB boundaries.

If older versions of parted (pre 2.1) or fdisk are used to create partitions, a manual calculation of partition boundaries will ensure optimum performance of Advanced Format disk drives. The partitioning tool needs to be set t work in units of sectors rather than cylinders or Megabytes for example. Under parted, enter:

unit s

For fdisk, simply entering "u" will toggle between cylinder and sector mode. Make sure that all partitions start on a multiple of 8 sectors (8x 512B = 4KB) and that partition sizes are multiples of 8 sectors. Make sure that there is space left at the start of partitions as required. For example on a boot drive, do not start at sector 0 as there needs to be space for the boot code. Sector 64 is a good start point or even 2048 which would be a 1MB boundary. Also extended partitions will need a gap between their start point and the first logical partition contained within them.

The file system defaults on most Linux systems are to use blocks of 4KB data. Typically no specific actions are needed to configure block sizes for WD Advanced Format drives. For options on block sizes for the mkfs tools, consult the "man" pages. Note that for the e2fstools used for file system creation, version 1.41.10 onwards will warn the user that they are attempting to make a file system on an unaligned partition. The user is advised to repartition appropriately.

The installation defaults for Linux distributions create partitions based on pre-defined rule sets which may not allow for Advanced Format drive geometry optimisation. Current distributions will probably require manual setup of partitions as described above. Before running the installation process, access a command line terminal and create the required partitions using parted or fdisk. Once created, use the installer's option to install on existing partitions rather than create a new or modified partition table. Assume that distributions released in 2009 or earlier will not take account of Advanced Format drives.

Western Digital has been working with the Linux kernel development teams and with the vendors of the some of the more popular Linux distributions. Starting with Linux Kernel Version 2.6.34, the latest stable kernel release, the default installations will align partitions to the most appropriate boundaries on Advanced Format disk drives. For example, the following distributions will default to good alignment for Advanced Format disk drives: Ubuntu 10.04, Fedora 13, Redhat 6 and derived products. It is also expected that by release time Debian 6 (Squeeze) and openSUSE 11.3 will have completed the changes required for the default installation to be well aligned.

Linux users that build their systems from the Linux distribution should refer to the "ATA 4 KiB sector issues" article on the Kernel.Org ATA Wiki at: ATA 4KiB Sector Issues Article.

[nukedathlonman]

Re: Advanced Format Hard Drive setup question

How odd, the begining and ending are divisible by 8.... And I have read that article before I bought the HD. And I know I've done everything right with partition alignment. Meh, for now I'll keep a back up and run it like this for the time being as everything looks and runs fine. I have a feeling the alignment software might be incorrect.

[GreyGeek]

Re: Advanced Format Hard Drive setup question

It's only 500GB. You could test it by creating a 1024 byte file of characters and then use the copy command to repeatedly paste itself to itself until you get a 32GB file, then copy & paste that until you begin to approach the limit of the drive. Just a thought. The more stuff you save on it before you learn you have problems the more difficult it will be to back it up.

[nukedathlonman]

Re: Advanced Format Hard Drive setup question

True enough! Thanks!

[GreyGeek]

Re: Advanced Format Hard Drive setup question

It's only 500GB. .....

When re-read what I wrote the world "only" stood out. In 1980 I had completed the computerization of a fastener store, selling screws, bolts, nuts, washers, snaps, etc... Thousands of them. The time needed to fill orders shrank from 4 or 5 people needing as many hours (orders in the morning, filing and shipping in the afternoon) to one person filling all orders from the parts inventory by making one pass, in less than an hour. He felt he could expand his inventory to grow his business because of his ability to quickly fill orders brought in new business.

A couple of months later he called me was was concerned that the two 5.25" floppy drives (Apple Disk ][+) would fill up within a few months. Re-evaluating his increase in inventory and business volume it became apparent he was right, the 1 1/2 floppy space assigned to data was already 3/4ths full. We settled on a 5MB Corvus disk drive. The Corvus required that it be turned on 15 minutes before the Apple was so that it could warm up and stabilize. Then the printers and the Apple could be turned on. The backup would be handled with a VHS tape recorder which was driven by the software Corvus supplied. It took EIGHT hours to back up and verify the 5MB Corvus with the VHS tape drive. From that time on neither the Corvus, the printers, the VHS or the Apple were ever turned off.

The first thing Wes, the owner, said when he saw the physical size (and data capacity) of that drive was "That's as big as a barn! We'll never be able to fill it up!".

Six months later he switched to an IBM PC with an internal 10MB HD because the Corvus was full. His son, Jim, a precocious high school student, showed so much interest in programming that I taught him how to program using the DOS based RDMS tool that I was using, "Advanced Revelation", based on the Pick DBMS. Jim took over the programming duties during his senior year, after graduation went on to earn a PhD in Computer Science.

Wes died a few years ago, but I've often wondered what he would think about Terabyte drives.