Crochet partition alignment
Bernd Walter
ticso at cicely7.cicely.de
Tue Sep 9 00:30:17 UTC 2014
[67]wandboard# gpart list
Geom name: mmcsd0
modified: false
state: OK
fwheads: 255
fwsectors: 63
last: 61497343
first: 63
entries: 4
scheme: MBR
Providers:
1. Name: mmcsd0s1
Mediasize: 52416000 (50M)
Sectorsize: 512
Stripesize: 4194304
Stripeoffset: 30208
Mode: r1w1e1
attrib: active
rawtype: 12
length: 52416000
offset: 8418816
type: !12
index: 1
end: 118817
start: 16443
2. Name: mmcsd0s2
Mediasize: 31425805312 (29G)
Sectorsize: 512
Stripesize: 4194304
Stripeoffset: 2114560
Mode: r1w1e2
rawtype: 165
length: 31425805312
offset: 60834816
type: freebsd
index: 2
end: 61497343
start: 118818
Consumers:
1. Name: mmcsd0
Mediasize: 31486640128 (29G)
Sectorsize: 512
Stripesize: 4194304
Stripeoffset: 0
Mode: r2w2e5
Geom name: mmcsd0s2
modified: false
state: OK
fwheads: 255
fwsectors: 63
last: 61378525
first: 0
entries: 8
scheme: BSD
Providers:
1. Name: mmcsd0s2a
Mediasize: 31425757184 (29G)
Sectorsize: 512
Stripesize: 4194304
Stripeoffset: 2162688
Mode: r1w1e1
rawtype: 7
length: 31425757184
offset: 48128
type: freebsd-ufs
index: 1
end: 61378525
start: 94
Consumers:
1. Name: mmcsd0s2
Mediasize: 31425805312 (29G)
Sectorsize: 512
Stripesize: 4194304
Stripeoffset: 2114560
Mode: r1w1e2
There are 63 sectors per track in MBR table.
s1 starts at sector 16443 in track 261.
This is an uneven 512 byte sector number, so it starts at 512 Byte
alignment only.
Leaves the question why 261 tracks are left out when it still isn't
aligned?
s2, which is what I care most about, starts at 118818.
This is even, but only once divideable by 2.
It is at a 1024 alignment - still not the needed >= 4k for SD cards.
Inside s2 the a partition starts at 48128 (+118818 from provider).
Again lost space.
By itself it would be a 512k alignment - more than perfect, though I
don't think it requires such a big waste, but with the mmcsd0s2 provider
alignemt it's still only 1k.
--
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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