Re: [RFC ONLY 3/8] btrfs: read raid-stripe-tree from disk

Qu Wenruo
2022-05-19T11:48:48Z

On 2022/5/19 19:44, Johannes Thumshirn wrote:
> On 19/05/2022 12:37, Qu Wenruo wrote:
>>> RAID1 on zoned only needs a stripe tree for data, not for meta-data/system,
>>> so it will work and we can bootstrap from it.
>>>
>> That sounds good.
>>
>> And in that case, we don't need to put stripe tree into system chunks at
>> all.
>>
>> So this method means, stripe tree is only useful for data.
>> Although it's less elegant, it's much saner.
>
> Yes and no. People still might want to use different metadata profiles than
> RAID1.

For RAID1 variants like RAID1C3/4, I guess we don't need stripe tree either?

What about DUP? If RAID1*/DUP/SINGLE all doesn't need stripe tree, I
believe that's already a pretty good profile set for most zoned device
users.

Personally speaking, it would be much simpler to avoid bothering the
stripe tree for metadata.

Thanks,
Qu

> I'd prefer to have system on RAID1 (forced) with stripe trees and
> data/meta-data can be whatever. Of cause only RAID5/6 or higher level encodings
> which might need a stripe-tree should be accpeted with a stripe tree.