Mac OS X 10.11.2: Mounting a damaged disk fails with no error message

Number:rdar://25280285 Date Originated:21-Mar-2016 04:22 PM
Status:Open Resolved:
Product:OS X Product Version:Mac OS X 10.11.2 (15C50)
Classification:Serious Bug Reproducible:Always
When Disk Utility fails to mount a disk, no error message or other user feedback is presented to indicate there’s a problem.

For example, I just tried to mount a disk and the only way I could figure out there was a problem was by looking at system.log:

Mar 21 16:16:46 CHOCKMASTER kernel[0]: jnl: disk5s2: open: journal magic is bad (0x0 != 0x4a4e4c78)
Mar 21 16:16:46 CHOCKMASTER kernel[0]: hfs: late jnl init: failed to open/create the journal (retval 0).
Mar 21 16:16:46 CHOCKMASTER kernel[0]: hfs_mounthfsplus: hfs_late_journal_init returned (0)
Mar 21 16:16:47 CHOCKMASTER kernel[0]: hfs_mounthfsplus: encountered error (22)
Mar 21 16:16:47 CHOCKMASTER kernel[0]: hfs_mountfs: encountered failure 22 
Mar 21 16:16:47 CHOCKMASTER kernel[0]: hfs_mount: hfs_mountfs returned error=22 for device disk5s2
Mar 21 16:16:47 CHOCKMASTER diskarbitrationd[75]: unable to mount /dev/disk5s2 (status code 0x00000001).
Mar 21 16:16:47 CHOCKMASTER storagekitd[29017]: Mount of disk5s2 blocked by dissenter PID=0 (kernel) status=0x0000c001 (Operation not permitted)
Mar 21 16:16:47 CHOCKMASTER Disk Utility[29016]: Could not mount disk: Error Code=49153 "(null)" UserInfo={DissenterPID=0, Dissenter=true, Target=disk5s2, Action=Mount, DissenterStatus=49153}

As you can see in the last log message, the error has propagated up to Disk Utility, but not to the user (who’s left wondering if there’s a problem or not.)


Interested to know if there was ever a resolution to this issue. I've had some trouble with a disk recently and got this error, even though Disk Utility and other tools said that the volume was fine. I'm still running El Capitan (10.11.6)

Anyway ... I was able to fix it by resizing the partition in Paragon Hard Disk Manager. Pretty sure that the partition information had somehow become corrupt and the resize rewrote the partition table entry. Note that disk utility wouldn't let me modify the partitions, hence Hard Disk Manager.

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