Mac OS X 10.5.3: Time machine drive gets changed to read-only

[Published Monday, June 9]

Time Machine drives may periodically change to read-only, depending on the circumstances of use. For some users, after updating to 10.5.3 they noticed this occurred with their TM drives. Additionally, while this problem appears to predominantly affect FireWire/USB drives, it has cropped up for some Time Capsule users as well. This behavior seems to occur in a random manner, as one user writes:

TerryWyse:

"Time Machine (or something) seems to be randomly setting my backup disk (external Western Digital "My Book Studio Edition" 500GB) to read-only which, of course, brings Time Machine backups to a halt. I can generally just restart my MacBook Pro and all is well again but then after a few more hourly backups, it will go back to read-only status again."

This appears to apply to the whole disk, as other partitions on the device become read-only as well even if they are not being used by TM. Upon checking the permissions of the drive using the get info window, it will list the owner as read-only, but other groups may have read and write access. Changing these attributes back manually seems to only be a temporary fix if possible, but for many users the drive gives an error saying the user does not have permission to change these attributes.

This problem has affected users before the 10.5.3 update and is spurred by putting the computer to sleep, indicating it's not solely caused by the update. As one user with 10.5.2 installed writes:

TJCourant writes:

"I have my computer set up to sleep when inactive. Upon awakening, frequently I will get an error where Time Machine indicates the storage drive (an external LaCie) is read only. Sure enough, I will open the drive, and get a read only indicator (the little pencil with a line through it)."

Fixes

Eject and/or change permissions settings on the TM drive In the Finder, right-click the time machine drive and eject it. Then unplug it, and plug it back in. For some users it may help to get info on the drive and uncheck the "ignore permissions" option. Then eject and unplug it, plug it back in, and run a drive repair on it using Disk Utility.

Clear the user immutable flag on the device Open the terminal and type this command in (without pressing enter yet):

• chflags nouchg

Then drag the problematic drive to the terminal window, which should enter the full path of the drive after the typed commands. Ensure there is a space between "nouchg" and the start of the drive path, and then press enter.

Feedback? Late-breakers@macfixit.com.

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