Re: Drives failures in irregular RAID1-Pool

[Andrei Borzenkov <arvidjaar@gmail.com>]

On 28.07.2023 18:26, Stefan Malte Schumacher wrote:
> Thanks for the quick reply. Is there any way for me to validate if the
> filesystem has redundant copies of all my files on different drives?

I can only think of "btrfs scrub".

> I read that it was suggested to do a full rebalance when adding a
> drive to a RAID5 array. Should I do the same when adding a new disk to
> my array?
> 

I do not know where you read it and I cannot comment on something I have 
not seen. But for RAID1 I do not see any reason to do it.

> Yours sincerely
> Stefan
> 
> Am Fr., 28. Juli 2023 um 17:22 Uhr schrieb Andrei Borzenkov
> <arvidjaar@gmail.com>:
>>
>> On 28.07.2023 16:59, Stefan Malte Schumacher wrote:
>>> Hello,
>>>
>>> I recently read something about raidz and truenas, which led to me
>>> realizing that despite using it for years as my main file storage I
>>> couldn't answer the same question regarding btrfs. Here it comes:
>>>
>>> I have a pool of harddisks of different sizes using RAID1 for Data and
>>> Metadata. Can the largest drive fail without causing any data loss? I
>>> always assumed that the data would be distributed in a way that would
>>> prevent data loss regardless of the drive size, but now I realize I
>>> have never experienced this before and should prepare for this
>>> scenario.
>>>
>>
>> RAID1 should store each data copy on a different drive, which means all
>> data on a failed disk must have another copy on some other disk.
>>
>>> Total devices 6 FS bytes used 27.72TiB
>>> devid    7 size 9.10TiB used 6.89TiB path /dev/sdb
>>> devid    8 size 16.37TiB used 14.15TiB path /dev/sdf
>>> devid    9 size 9.10TiB used 6.90TiB path /dev/sda
>>> devid   10 size 12.73TiB used 10.53TiB path /dev/sdd
>>> devid   11 size 12.73TiB used 10.54TiB path /dev/sde
>>> devid   12 size 9.10TiB used 6.90TiB path /dev/sdc
>>>
>>> Yours sincerely
>>> Stefan Schumacher
>>