Linked by theosib on Sun 14th Feb 2010 10:45 UTC
Linux

Recently, I bought a pair of those new Western Digital Caviar Green drives. These new drives represent a transitional point from 512-byte sectors to 4096-byte sectors. A number of articles have been published recently about this, explaining the benefits and some of the challenges that we'll be facing during this transition. Reportedly, Linux should unaffected by some of the pitfalls of this transition, but my own experimentation has shown that Linux is just as vulnerable to the potential performance impact as Windows XP. Despite this issue being known about for a long time, basic Linux tools for partitioning and formatting drives have not caught up.

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RE[2]: geez
by sj87 on Mon 15th Feb 2010 14:10 UTC in reply to "RE: geez"
sj87
Member since:
2007-12-16

I think I might have the same problem. What model are you talking about?
mine is WD15EADS.


Currently the only "Advanced Format" disks (as WD calls it) are the Green models ending in "EARS". WD15EADS is of the previous generation and therefore not affected.

The Advanced Format disks are called WD10EARS, WD15EARS and WD20EARS.

Hm, how is LBA addresses specified exactly?

I thought it was specified as multiples of drive sector size, in which case addressing via LBA should always be aligned - but is it in reality always a multiple of 512?


I read that every major HDD manufacturer has agreed to using a 512-byte-emulation mode until the end of 2014.

I also read that there is a way for software to ask the disk about its real physical layout but that Western Digital hasn't implemented such feature in its current line of 4k disks. Therefore no software can detect them and take care to stay aligned.

Edited 2010-02-15 14:11 UTC

Reply Parent Score: 1

RE[3]: geez
by soulrebel123 on Tue 16th Feb 2010 17:57 in reply to "RE[2]: geez"
soulrebel123 Member since:
2009-05-13

I know it is not supposed to be an advanced format drive, but running the code at the and of the article indeed shows performance differences with alignment other than 0 and 8. (I ran it on a partition starting at sector 64)

Also the disk freezes a lot when doing io.

I am sending it back.

Reply Parent Score: 1

RE[3]: geez
by kjmph on Wed 17th Feb 2010 18:12 in reply to "RE[2]: geez"
kjmph Member since:
2009-07-17

Where did you get this info? If you read WD's site:

http://www.wdc.com/en/products/products.asp?driveid=773

Formatted Capacity 2,000,398 MB
Capacity 2 TB
Interface SATA 3 Gb/s
User Sectors Per Drive 3,907,029,168

That's 512 byte sectors, model # WD20EARS

Reply Parent Score: 1