Hello,
I am trying to use pyanaconda.storage to get overview of installed
storage facilities and I have troubles counting free space on a disk.
Consider a (virtual) disk with 10 partitions, created by Anaconda (code
is below). pyanaconda.storage.partitioning.getFreeRegions([disk]) returns:
parted.Geometry instance --
start: 63 end: 2047 length: 1985
-> the first sector is MBR. Why there are additional 62 sectors skipped
before the first free region? Is it because of alignment rules?
-> why Anaconda leaves the first megabyte free? Boot loader/grub? I did
not request any.
The rest of primary partitions are fine, without any gaps. Logical
partitions are quite different:
start: 63551 end: 64259 length: 709
This free region is at the beginning of the extended partition. The
extended partition starts at sector 63488 and the first logical
partition starts at 67584.
-> Why there is a free space at all? I did not request any.
-> What are 3325 sectors between the free space end and the first
logical partition start? I know, there is one sector for logical
partition metadata, but 1.6MB, which is not part of any partition nor
free space region, seems too much to me.
-> Similarly, what are 63 sectors between the extended partition start
and the free space start? 1 sector is for logical partition metadata,
but the rest?
start: 110592 end: 112454 length: 1863
This is a free space between two logical partitions.
-> Again, why is the free region here? And there are 186 'hidden'
sectors between this free space end and start of the next logical partition.
If the alignment to cylinder boundary is cause of these weird numbers,
can I turn the alignment off in pyanaconda.storage? The numbers
reported by disks are completely artificial anyway these days.
Thanks in advance for any partitioning insight.
Jan
Gory details
------------
Sample code to create 10 partitions:
<initialization omitted>
disk = storage.devicetree.getDeviceByName('sda')
for i in range(10):
part = storage.newPartition(disks=[disk], size=10)
storage.createDevice(part)
pyanaconda.storage.partitioning.doPartitioning(storage=storage)
storage.devicetree.processActions(dryRun=False)
complete print of pyanaconda.storage.partitioning.getFreeRegions([disk]):
parted.Geometry instance --
start: 63 end: 2047 length: 1985
device: <parted.device.Device object at 0x1efa6d0> PedGeometry:
<_ped.Geometry object at 0x1efa690>
parted.Geometry instance --
start: 63551 end: 64259 length: 709
device: <parted.device.Device object at 0x1efa710> PedGeometry:
<_ped.Geometry object at 0x1efa4d0>
parted.Geometry instance --
start: 110592 end: 112454 length: 1863
device: <parted.device.Device object at 0x1efa190> PedGeometry:
<_ped.Geometry object at 0x1efa650>
parted.Geometry instance --
start: 223232 end: 2097151 length: 1873920
device: <parted.device.Device object at 0x1efab10> PedGeometry:
<_ped.Geometry object at 0x1efa0d0>
fdisk output:
Disk /dev/sda: 1073 MB, 1073741824 bytes
34 heads, 61 sectors/track, 1011 cylinders, total 2097152 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 identifier: 0xc9797763
Device Boot Start End Blocks Id System
/dev/sda1 2048 22527 10240 83 Linux
/dev/sda2 22528 43007 10240 83 Linux
/dev/sda3 43008 63487 10240 83 Linux
/dev/sda4 63488 2097151 1016832 5 Extended
/dev/sda5 67584 88063 10240 83 Linux
/dev/sda6 90112 110591 10240 83 Linux
/dev/sda7 112640 133119 10240 83 Linux
/dev/sda8 135168 155647 10240 83 Linux
/dev/sda9 157696 178175 10240 83 Linux
/dev/sda10 180224 200703 10240 83 Linux
/dev/sda11 202752 223231 10240 83 Linux
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