Disk layout for XO-1.5

[Mitch Bradley]

The filesystem is no longer internally compressed.  The current size for 
the XO-1.5 system is 1.1 GB.  2 GB gives some headroom for growth and 
for temporary overages during updates.

Walter Bender wrote:
> Why such a large system partition?
>
> -walter
>
> On Mon, Jul 27, 2009 at 6:17 PM, Mitch Bradley<wmb at laptop.org> wrote:
>   
>> This is a request for comments on a proposed disk layout for XO-1.5.
>>
>> XO-1.5 will have "managed NAND" instead of raw NAND, so we can use
>> conventional filesystems instead of e.g. JFFS2.
>>
>> Proposal:
>>
>> The internal NAND storage will be partitioned with an FDISK partition
>> map, into three partitions:
>>
>> /boot - 50 MB - FAT16
>>    Contains olpc.fth, vmlinuz, initrd, and any other files that OFW
>> needs to access during booting
>>
>> / - 2 GB - ext4
>>    Contains system files
>>
>> /home - remainder of storage - ext4
>>    Contains user files
>>
>> Dual-boot systems might have additional partitions for Windows.  That
>> will probably require storage devices > 4GB.
>>
>> The partitions will be aligned to at least 1 MiB boundaries, ensuring
>> that they do not split internal NAND erase blocks.
>>
>> The choice of FAT for /boot makes it usable for both Linux and Windows.
>> The choice of FAT16 avoids any possible patent issues surrounding
>> FAT32.  FAT16 works fine for 50 MB partitions, using a 1K cluster size.
>> With larger cluster sizes, there are several factors of two of headroom
>> - and large clusters are not a problem for /boot, which tends to contain
>> mostly large files.
>>
>>
>>
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>>     
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