Gnome Disk Utilty calculates new raid partion sizes incorrectly.

[Paul Gregg]

Binary package hint: gnome-disk-utility

In a new testbed, 4 drive NAS type system with Ubuntu 10.10, I used the Disk Utility with a pair of 160GB Seagate Barracuda 7200.7 (ST3160023AS) drives. I initially created a mirror set and all was ok.

I then pulled the first 160GB drive (hot-swap) and plugged in a 2TB WD20EARS "green" drive.

Disk Utility correctly changed the raid array to Degraded, and presented the new clean 2TB drive. In the Raid Array configuration, I chose to Edit the components and Add a new drive/partition to the raid set. I selected the 2TB drive and the utility declared it would create a 160GB partition leaving the rest of the disk free. All ok I thought, except when I clicked through to complete the operation I received the error message:

Error adding spare: mdadm exited with exit code 1: mdadm: /dev/sdb3 not large enough to join array

How this happened is this. the original size of the partitions from the 160GB disks were 160,041,833,984 bytes.
The partition that Disk Utility created were 160,039,239,680 bytes - obviously - mdadm then rejected this partition as too small.

I manually created a partition (fdisk -u ) of sufficient size, and was able to manually add this to the raidset with mdadm. The GUI tool did not let me choose the existing partition to add to the set.

Separately, I note that the too begins at sector 63 on the disk - this is bad thing to do on these large format drives since internally they use 4KB block sizes and you should start/stop your blocks on these boundaries. Defaulting to block 63 means that for every block write, the drive must read the existing block, modify the bytes which will change and rewrite the block. This slows down write access to approx 1MB/sec. When partitioning/formatting large format drives, you should start at sector 64 (use -u flag to fdisk when doing this manually).

Thanks,
Paul Gregg

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: gnome-disk-utility 2.30.1-2
ProcVersionSignature: Ubuntu 2.6.35-22.35-generic 2.6.35.4
Uname: Linux 2.6.35-22-generic i686
Architecture: i386
Date: Mon Nov 15 15:39:10 2010
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_GB.utf8
 SHELL=/bin/bash
SourcePackage: gnome-disk-utility

[Pedro Villavicencio (pedro)]

Thanks for the report, it has been some time without any response or feedback in this bug report and we are wondering if this is still an issue for you with the latest release of Ubuntu the Natty Narwhal, May you please test with that version and comment back if you're still having or not the issue? Please have a look at http://www.ubuntu.com/download to know how to install that version. Thanks in advance and sorry for the late response.

[Launchpad Janitor (janitor)]

[Expired for gnome-disk-utility (Ubuntu) because there has been no activity for 60 days.]