Red Hat Bugzilla – Bug 990469
ARM images have unaligned partitions
Last modified: 2015-01-10 05:29:34 EST
Normally partitions created by either fdisk or parted are aligned to a multiple of 1MiB, so usually a multiple of 2048 sectors, for the F-19 arm images this is not the case, they don't seem to have any alignment at all, which is bad for performance:
[hans@localhost ~]$ sudo fdisk /dev/loop5
Welcome to fdisk (util-linux 2.23.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/loop5: 7889 MB, 7889485824 bytes, 15409152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0006ca47
Device Boot Start End Blocks Id System
/dev/loop5p1 1953 1001953 500000+ 83 Linux
/dev/loop5p2 1001954 2001953 500000 83 Linux
/dev/loop5p3 2001954 14697265 6347656 83 Linux
This is also what is breaking rottfs-resize, as it re-creates p3 using fdisk which will then properly align
the partition start, making it different from what it was before.
This package has changed ownership in the Fedora Package Database. Reassigning to the new owner of this component.
Created attachment 880547 [details]
patch: use pated 'optimal' alignment instead of non-optimal cylinder alignment
This patch goes with the upstream appliance-tools on fedorahosted:
It leverages 'parted -a optimal' instead of 'cylinder' based alignment.
Tested with ARM generated images only, but should be fine for cloud images too.
With optimal alignment, the starting offset of the first partition is 2048, instead of 1953 with cylinder alignment.
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