My Book 2TB upgrade to 4TB


I have had a drive failure (a WD10EACS) in my 2TB My Book II WD20000C033-000. Since the unit was configured on my Mac as RAID0 and was used for Time Machine, my loss is minimal.

I’d like to replace both the WD10EACS drives with new WD20EARS 2TB drives, hoping that the WD RAID Manager on my Mac can format the My Book as a fresh 4TB RAID0 device. Seems to me that I have a good enclosure, power supply and all the mounting hardware for new drives, so I may as well gain extra capacity.

Has anybody had any experience with this approach - data loss and (now out-of) warranty issues aside.


Bought two WD20EARS drives and inserted them. All looked OK, but RAID0 HFS+ only formats to about 1,678.02 MB using WD RAID Manager v2.25, but RAID1 HFS+ formats to 1,863.01 MB. RAID0 certainly isn’t giving me 4TB. And I’m not sure why RAID0 gives less than RAID1. Perhaps it’s related to drive formatting - I think these drives use 512byte blocks by default, unless you use a driver that supports the 4K block formatting

I installed 1.08a firmware before inserting the drives, so I guess there’s not much else I can do.

D-Link DNS-323 box may be the next option for me. Or my much lusted-after Drobo!!


Hi Gary, I am having the same problem with my MyBook mirror edition. I also have a Studio edition 2 wich I successfully upgraded after having to switch it to raid 1 fat32, then raid 0 fat32 (which then finally recognized as all 4tb) before formatting it to hfs+. Alas, this hasn’t worked for the Mirror edition. (the drive manager software definately has a few bugs). Im talking to support about this issue and will update you if I have any luck. Cheers. Matt Btw, im also thinking if dumping the mybook range and going to a nas, maybe a DIY unRAID box

Well… Yesterday I purchased 2 x 2TB WD Green to upgrade to 4TB in My Mirror … Tried to get more than 2TB in any availlable formating, and than I found your info on this forum…

You mentioned that you are talking with support about this issue on Mirror edition…

Any chance that you got any solution.