Re: [PATCH] md/raid0: Fail BIOs if their underlying block device is gone

[Reindl Harald <h.reindl@thelounge.net>]

Am 29.07.19 um 22:27 schrieb Guilherme G. Piccoli:
>> If that's correct, then this seems to be a critical weak point in cases when
>> we have a RAID0 as a member device in RAID1/5/6/10 arrays.
> 
> Hi Roman, I don't think this is usual setup. I understand that there are
> RAID10 (also known as RAID 0+1) in which we can have like 4 devices, and
> they pair in 2 sets of two disks using stripping, then these sets are
> paired using mirroring. This is handled by raid10 driver however, so it
> won't suffer for this issue.
> 
> I don't think it's common or even makes sense to back a raid1 with 2
> pure raid0 devices.
if i would have been aware that RAID10 don't support "--write-mostly" to
make a hybrid HDD/SSD RAID (https://www.tansi.org/hybrid/) i would
likely have done exactly that to buy only 2 instead 4 x 2 TB SSD disks
here and frankly i have another 5 machines where this limitation of
RAID110 on linux sucks