Re: Enhancement Idea - Optional PGO+LTO build for btrfs-progs

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

On 2021/7/14 下午8:35, Neal Gompa wrote:
> On Wed, Jul 14, 2021 at 5:22 AM DanglingPointer
> <danglingpointerexception@gmail.com> wrote:
>>
>> Yes noted.
>>
>> We're aware of the write hole risk.  We have battery backup for both
>> workstations and automation to shut it down in the event of power-outage.
>>
>> Also they are lab workstations. Not production.  Data is backed up to
>> two locations.
>>
>> The primary reason for RAID5 (or 6) is economics.  Money goes way
>> further with RAID5 compared to other RAIDs (1,/10,etc) for the amount of
>> data store-able in an array with the reliability of being able to loose
>> a disk.  I'm sure there are thousands of others out there in a similar
>> situation to me where economics are tight.
>>
>> Would be good if at some point RAID56 can be looked on and fixed and
>> further optimised so it can be declared stable.  Thousands of people
>> would further flock to btrfs, especially small medium enterprises, orgs,
>> charities, home users, schools and labs.
>>
>
> Btrfs RAID 5/6 code is being worked on[1], so this will be fixed
> eventually. I personally look forward to this being resolved as
> well...
>
> [1]: https://lore.kernel.org/linux-btrfs/BL0PR04MB65144CAE288491C3FC6B0757E7489@BL0PR04MB6514.namprd04.prod.outlook.com/
>
 From what I know, to solve the RAID5/6 write hole, the real solution
will be a journal, just like what all other soft raid56 does.

This means, we will have a new RAID5/6 profile other than the current
non-journaled RAID5/6.

Existing users still need to convert to the new profiles, not something
will be fixed magically.

Thanks,
Qu