Re: Idea: Use extended blocklist format to support installing to raid device.

[Bean]

On Tue, Aug 12, 2008 at 4:57 PM, Robert Millan <address@hidden> wrote:
> On Tue, Aug 12, 2008 at 09:38:52AM +0800, Bean wrote:
>> Hi,
>>
>> Currently, the blocklist format can only support traditional disk. I'm
>> thinking about a new format that can be used in raid as well.
>>
>> The new format is like this:
>>
>> checksum_0 blocklist_0 checksum_1 blocklist_1 ...
>>
>> The checksum is the checksum of sectors in the blocklist that follows.
>> For example:
>>
>> c1 10+20,40+10 c2 10+50
>>
>> This means 10-30,40-50 sectors from one disk, then 10-60 sectors from
>> another disk. The checksum is used to find the correct disk.
>>
>> For traditional disk, we can also use this format, for example:
>>
>> c1 10+20,40+10
>>
>> This can support install to different disk than the one core.img is
>> in, as it will scan all disks for the correct checksum at runtime.
>
> IMHO, I think we should try to get rid of blocklists, or avoid reliing on
> them as much as possible.  Specially now that we have a good compression
> ratio for msdos partmaps, and plenty of space on gpt ones.

Hi,

Right, but we can't get rid of it totally. For example, if they don't
reserve enough space at the beginning of disk, there is no way to
install grub2 without blocklist. And, some people may want to install
to partition instead of mbr. blocklist is useful in small media as
well, like floppy, which don't the luxury of mbr.

-- 
Bean