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_______0 Guru
Joined: 15 Oct 2012 Posts: 521
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Posted: Sat May 25, 2013 7:48 pm Post subject: insane block device notation!! |
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hi,
I was trying to re-create exact size of a partition but I was faced with a huge problem about size conventions. They are anything but fsck,ed up.
to illustrate the problem.
Device Boot Start End Blocks Id System
/dev/sdXX * 2048 206847 102400
then fdisk ask to add numbers with K,M or G. I substracted 2048 from 206847 to get the value. I added M and resulted in out of range, added K and it was off. Then out of sheer luck I tried +100M just because I saw that number under gparted and resulted in the exact 206847 end range number.
This means that fdisk's 100M is exactly 204799 blocks!! wtf...
How on earth is possible to create accurate partitions with sane numbers???
Gparted, and kde's partition utility got the same darn problem. When adjusting is always some uneven numbers that don't correspond to the powers of 2.
I hate to have uneven partitions.
How to add the perfect numbers that always approximate multiple of 2?
thanks. |
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NeddySeagoon Administrator
Joined: 05 Jul 2003 Posts: 54237 Location: 56N 3W
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Posted: Sat May 25, 2013 8:26 pm Post subject: |
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_______0,
The partition you posted starts at block 2048 and ends at block 296847 (both numbers inclusive) so the partition contains a even number of blocks.
In this case, 204800
You have provided an example of the off by one error. A block is 512B so the size is 102400k.
Its the wonders of mixed binary and decimal arithmetic.
If you use a +, the partition is set that far from the start e.g. +100M
If you omit the + them number is used at the absolute end, in whatever units have set in fdisk. Usually blocks but cylinders still work. _________________ Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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