Encrypted external drive usually prompts for password, despite being in keychain

Question

I have an external encrypted drive, and almost every time I plug it in, it'll ask me for the password, even though it's already in my keychain. If I type the password in, it'll mount as expected. Oddly, if I hit cancel, it still mounts anyway, presumably because the password is in the keychain.

The problem is that it prompts for a password each time, even though it clearly doesn't need it because the password is in the keychain.

Possible oddities/useful details:

• Mac OS X 10.9.1 Mavericks (though not a recent issue)
• USB3 Guardian Maximus (2x 2TB HDDs in RAID1)
• Drive is partitioned into two Logical Volume Groups each with a Logical Volume Partition, Formatted as Mac OS Extended (Journaled, Encrypted)

On plugging in the disk, I get the following in the Console:

21/02/2014 9:41:22.000 am kernel[0]: USBMSC Identifier (non-unique): 20202020202020202020202036564D4344594535 0x525 0x3100 0x0, 3
21/02/2014 9:41:24.000 am kernel[0]: CoreStorage: fsck_cs has finished for group "BB4FAC13-41D6-4432-BBE6-BFC79161DE11" with status 0x00
21/02/2014 9:41:24.000 am kernel[0]: CoreStorage: fsck_cs has finished for group "9072D797-3F1C-447C-9EF7-801428DB9C8B" with status 0x00
21/02/2014 9:41:24.799 am com.apple.kextd[12]: LVG changed
21/02/2014 9:41:24.801 am com.apple.kextd[12]: LVG changed
21/02/2014 9:41:24.000 am kernel[0]: CoreStorageFamily::unlockVEKs() failed to unwrap the vek, status = e00002bc
21/02/2014 9:41:25.021 am com.apple.kextd[12]: LVG changed
21/02/2014 9:41:25.000 am kernel[0]: CoreStorageFamily::unlockVEKs() failed to unwrap the vek, status = e00002bc
21/02/2014 9:41:25.025 am com.apple.kextd[12]: LVG changed

After mounting, it just says: (PARTITION_# are partition labels)

21/02/2014 9:41:25.000 am kernel[0]: hfs: mounted PARTITION_1 on device disk3
21/02/2014 9:41:53.000 am kernel[0]: hfs: mounted PARTITION_2 on device disk4

---

Update

I did the keychain repairs/resets as suggested by @megadroid and things seemed better briefly, but still not 100% reliable.

What I've noticed since then is that it's much more likely to mount cleanly (without the redundant password prompt) if the computer is unlocked, whereas if it's asleep or locked (i.e. password required after screensaver activates) then they won't mount cleanly.

Haven't really tested this thoroughly, but am wondering if it's actually something completely different, like the locked/unlocked state of my account (and perhaps therefore my keychain?), that causes the prompts to appear and the disk to fail auto-mounting.

Update 2:

Just plugged it in, everything mounted cleanly/without prompt before I'd logged in. So it's not the keychain being locked while the computer is locked.

Answer 1

Two things you can try are key chain first aid and keychain reset, altough these in-house solutions hardly ever fixed anyhting for me. This is based on the fact that when some apps keep asking for passwords stored in the keychain, it's sometimes related to a corrupt keychain DB (Address Book's empty DB comes already corrupt on every new Mac - sarcasm).

Answer 2

To me Key Chain First Aid did not identify any problems, but removing the corresponding entries from the keychain and entering them again next time I plugged in the external drive solved the problem (for the last two starts ;)