Re: Ideas for a feature implementation

[Konstantinos Skarlatos <k.skarlatos@gmail.com>]

On 13/8/2014 2:01 μμ, David Pottage wrote:
>
> On 12/08/14 12:00, Konstantinos Skarlatos wrote:
>> Maybe help with Andrea Mazzoleni's New RAID library supporting up to 
>> six parities? It seems to be a great feature for btrfs.
>>
>> https://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg31735.html
>
> That would be very cool, but at present vanila RAID 5 or 6 does not 
> work properly, so I think getting that fully working would be a better 
> idea. (Unless it would make more sense to merge the whole lot into one 
> bit of work where RAID 5 or 6 are just a special case of arbitrary 
> parity level support).
>
> At present, you can write RAID 5 or 6 data, but if anything goes 
> wrong, btrfs cannot use the parity information to help you get your 
> data back, so in general you are better off with RAID 1 or 10. Also, I 
> don't think I/O done in parallel so you get no speed advantage from 
> having multiple discs either.
>
Yeah, thats one of the features I am waiting to get finished, because I 
already have 5 multi disk systems that i would prefer to migrate to 
RAID5/6 from RAID1/JBOD that they are now.

I dont know what is the best sequencing, I just think that these are 
great patches/features and its a pity for them to languish.


-- 
Konstantinos Skarlatos