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Info on WD's new 'Advanced Format' drives (WD claims no issues w/OS X or Linux...)
From a reader mail this weekend. (Updated - see below for reader reply with info on new format (4k sectors) drive models and later comments from the reader with (std format) 2TB GP drive problems.)

"Any weird experiences with a WD Caviar Green drive and Macs?
I've been prowling around the net and can't see anything similar to this situation, well, on the Mac side. Maybe readers of will have ideas?

Background: WD is claiming that their new Green Caviar drives are now, at the lowest hardware level, designed for 4k blocks and as a result, Windows users need to 'align their partitions' to match the 4k block size. Fair enough. As far as WD is concerned, this is the only OS that has a problem, the rest (specifically mentioned Linux/Mac OS) should be fine. ( - "Advanced Format Hard Drive Download Utility - About Advanced Format Hard Drives")
This is not entirely the case:
Linux Not Fully Prepared for 4096-Byte Sector Hard Drives (OSnews Article from Feb 14th)
So perhaps this is the origin of a remarkably SLOW drive response after many many hours of usage. Now the problem is that I've gone through two WD Caviar Green drives. (Both connected to the internal SATA of a MacPro2,1). The heads make a recurring 'ka-click' or 'seeking sound' and the whole system slows down monumentally. (SMART data FWIW show no problems). (That sounds like its drive APM related, but usually that's only been an issue for notebook drives. However these are "green" models so perhaps it could be. I asked if he had something like Smart Utility for OS X to monitor the rate of load cycles (i.e. to see if a high rate of them) or any other SMART errors (bad sectors, ECC errors, etc).-Mike)
Initially I thought this might be a bad drive, so WD sent me a replacement drive (firmware 01.00A01) made late January and all seemed fine. After a week of moderate use, things aren't fine. Whole system started lagging again. So as I see it I'm dealing with either

a) a firmware incompatibility issue with the Mac and how it deals with this particular drive via SATA
b) a drive block size issue (odd to consider since HFS+ is 4k-block-sized based)
(FYI - he later said he -does not- have an "advanced format" (4K) drive - see later comments below.)
c) two bad drives

No kernel/disk I/O errors are reported in Console logs.
thx for a great site!

My first question to him was if his drive had any info on the label about the new format as the WD article includes this note down the page:

"What models utilize Advance Format technology?
Some models of the WD Caviar Green are built using Advanced Format. Over time more models and capacities will be added. WD drives with Advanced Format include special installation information on the drive label so be sure to read the label on your drive before installing it."

Last month I bought a 2TB WD Green drive (retail boxed model "WD20EADS" on label, on sale at a local store which may be old stock) and didn't see any notes about advanced format on it. (There were notes on jumper settings for 1.5TB, power up in standby, etc.) I've only used it so far as a media storage drive for my O!Play Air (Single partition, HFS+ formatted but MBR.
Back on Dec. 22nd (2009) I posted a reader's comments on problems with a batch of 1.5TB GP drives he bought back then, but he was using them for RAID (not recommended for Green drives) and other reader replies to that post noted no issues with them in non-RAID use. (But not sure when WD made this change in production or if his batch could have been the new format.)
Update: Shortly after posting this a reader replied with info on the new format model ID differences:

"I have their new 2TB (GP) drive, manufactured the final week of 2009. (Advanced format drives have EARS in the model name, as opposed to EADS in the old stock. The new drives will contain a sticker on the anti-static bag about Advanced Format limitations for certain OSes, such as WinXP, etc.)

The firmware I have is 80.00A80 and I'm using it on a 2008 Mac Pro (3,1). It's solely used as a Time Machine drive on Mac OS X 10.6.2, and after 2 weeks of constant use there's been no issues. I'll let you know if this changes, but for now I'm happy with it.
Joey K."

I wrote "D" to ask about his model ID on the label, as despite his comment on "late Jan" mfg, from the firmware version it's likely an older (EADS) model but want to confirm that. (He later wrote it's a EADS model)
FYI: Here's a Western Digital doc with Specifications for the WD Caviar Green (Advanced Format) SATA hard drives (WD20EARS, WD15EARS, WD10EARS, WD8000AARS, WD6400AARS) that also notes they have 64MB cache (vs 32MB with earlier series format Green drives)
Update - Here's later comments from "D":

" Load Cycle counts: this is a 'bug' or 'feature' that can't be generated on demand, the drive has to be running constantly for a few days before this odd head-seek behaviour is noted. Rebooting will give another day or two of peace and then after that the system will seize as it tries to access the drive and the drive doesn't respond. Perhaps the drive is doing an 'deep recovery mode' which is why these drives have been advised against use on some NAS forums which support multiple drive units in RAID configuration.

    Advanced Format notes: my mistake then, since this is definitely a WD20EADS w/32MB Cache and not an WD20EARS. Did not realize that R=Advanced Format and D=default/legacy. After a bit of digging at the site:

  • R Series: Specifications for the WD Caviar Green (Advanced Format) SATA hard drives ( WD20EARS, WD15EARS, WD10EARS, WD8000AARS, WD6400AARS)

    Whereas this particular drive is covered by the WD technote:

  • D Series: "Specifications for the following Western Digital Caviar Green and Caviar GP Serial ATA hard drives. WD5000AAVS, WD5000AACS, WD5000AADS, WD6400AAVS, WD6400AACS, WD7500AAVS, WD7500AACS, WD7500AADS, WD10EAVS, WD10EACS, WD10EADS, WD15EAVS, WD15EACS, WD15EADS, WD20EAVS, WD20EACS, WD20EADS"

    But then.... that makes this even more puzzling... why would a drive (esp. one fresh from factory) be going into head-recalibration/recovery mode so much that it'll hold/seize the SATA connection?
    (But if it did that - I'd think you'd see some log messages related to that. You mentioned earlier seeing none.-Mike)
    I can understand one drive being marginal or DOA, but another fresh from the factory and barely a month old from date of manufacture would supposedly have the latest firmware.

    Replaced the WD20EADS with a (7200rpm) Hitachi 2TB Deskstar (stunning read/write rates) and system hangs have disappeared. Very odd.

  • I've only used WD "Green" drives in some external cases where I wanted low power/cooler running - such as in my Ministack as I mentioned back in fall 2008 when I put a WD 1TB Green Gen2 (32MB cache/3 platter) in it. (It's been used daily in the ministack with my primary work machine. And zero problems to date with it. Slept and woke dozens of times a day - I normally disable HD sleep and just manually sleep the system when desired.)
    I chose higher performance (non-green) drives for the Mac Pro. (And as I mentioned before - I like the 1TB WD Caviar Blacks, which are around $100 on sale.) But I'd pick the ($179 currently) 2TB Hitachi 7200rpm drive over a 2TB WD Green for internal use.

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