Re: single disk reed solomon codes

["Ahmed Kamal" <email.ahmedkamal@googlemail.com>]

An experiment of applying RS codes for protecting data, worth a look
http://ttsiodras.googlepages.com/rsbep.html

He overwrites a series of 127 sectors and still manages to correctly
recover his data. We all know disks give us unreadable sectors every
now and then, so at least on workstations/laptops this could really be
useful ?

Advantage over single-disk-raid1 is storage efficiency (4.2MB becomes
5.2MB), that means we get 80% of useable disk space, instead of 50% if
I decide to raid1 everything ?

On Mon, Jul 21, 2008 at 6:03 PM, Dongjun Shin <djshin90@gmail.com> wrote:
> On Mon, Jul 21, 2008 at 4:40 PM, Ahmed Kamal
> <email.ahmedkamal@googlemail.com> wrote:
>> I definitely hope btrfs has this per-object "copies" property too.
>> However, simply replicating the whole contents of a directory, wastes
>> too much disk space, as opposed to RS codes
>>
>
> Although adding redundancy mechanism will help increasing the integrity of data,
> I'm not sure whether repeating the same kind of mechanism twice will help.
> (AFAIK, RS is common in HDD and BCH is common in flash due to their own
> physical characteristics)
>
> I think it is better to have another redundancy mechanism (like RAID1)
> which is independent of the algorithm used by the underlying storage.
>
> --
> Dongjun
>