Re: RAID-[56] stabilisation

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2022/4/20 10:17, Qu Wenruo wrote:
>
>
> On 2022/4/20 07:02, Roy Sigurd Karlsbakk wrote:
>> Hi all
>>
>> It's been a wee bit more than a decade since I started to look into
>> btrfs as a possible ZFS replacement. I just wonder when one can expect
>> RAID-[56] to stabilise as in usable for production, since this is, for
>> my use, rather critial.
>
> Currently the main problem for btrfs RAID56 is write-hole.
>
> To solve it, either we need a big feature in extent allocator (to avoid
> allocate extents in the partial written stripe), or go traditional
> journal based RAID56 (needs a new on-disk format change, and new code).
>
>
> If your use case can rule out power loss (by using UPS) and unexpected
> shutdown (no way to prevent kernel panic though), OR you can afford a
> full btrfs scrub before any write (can be very time consuming),

I mean "before any write after an unexpected shutdown/crash"

If you can ensure your fs is shutdown cleanly, then no problem at all.

> you can
> try btrfs RAID56.
>
> There is some plan to implement a RAID56 journal, but there is no
> concrete time table for that yet.
>
>
> Or, you can run single device btrfs on md/dm-raid56.
>
> Thanks,
> Qu
>
>>
>> Vennlig hilsen / Best regards
>>
>> roy
>> --
>> Roy Sigurd Karlsbakk
>> (+47) 98013356
>> http://blogg.karlsbakk.net/
>> GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt
>> --
>> I all pedagogikk er det essensielt at pensum presenteres
>> intelligibelt. Det er et elementært imperativ for alle pedagoger å
>> unngå eksessiv anvendelse av idiomer med xenotyp etymologi. I de
>> fleste tilfeller eksisterer adekvate og relevante synonymer på norsk.