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

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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by sj87 on Sun 14th Feb 2010 13:24 UTC
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I did battle with this issue just this morning. I had to manually configure the partitions to both begin and be length of multiples of eight using parted.

I didn't actually suffer of major read/write performance loss, only some random reads made the drive go crazy and very slow. Write speed topped at 70 MB/s, and after setting the partitions well-aligned it has gone up to 80 MB/s.

It has been suggested that WD might internally offset block addresses by 1 so that LBA 63 maps to LBA 64. -- I performed a test that demonstrates that WD has not done this

You're both wrong and wrong. It's a hack mode that can be enabled by connecting pins 7-8 on the HDD. But of course it's not enabled by default, because it would totally screw up every other OS.

Edited 2010-02-14 13:25 UTC

Reply Score: 3

RE: geez
by soulrebel123 on Sun 14th Feb 2010 17:28 in reply to "geez"
soulrebel123 Member since:

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

Perhaps not only linux is not ready. They are not ready even at WD support.

Reply Parent Score: 1

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

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