On 29/07/2019 17:18, Roman Mamedov wrote: > On Mon, 29 Jul 2019 16:33:59 -0300 > "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxxxxx> wrote: > >> Currently md/raid0 is not provided with any mechanism to validate if >> an array member got removed or failed. The driver keeps sending BIOs >> regardless of the state of array members. This leads to the following >> situation: if a raid0 array member is removed and the array is mounted, >> some user writing to this array won't realize that errors are happening >> unless they check kernel log or perform one fsync per written file. >> >> In other words, no -EIO is returned and writes (except direct ones) appear >> normal. Meaning the user might think the wrote data is correctly stored in >> the array, but instead garbage was written given that raid0 does stripping >> (and so, it requires all its members to be working in order to not corrupt >> data). > > 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. Thanks for your comment! Cheers, Guilherme
