Does replacing a mirror drive in a 2 drive VDEV cause entire pool to resliver?

Back when I set this guy up years ago, I thought that using multiple vdevs with 2 drive mirrored was supposed to only cause limited reslivering?
No rush, just curious.

Welcome to the forums!

Yes, a Mirror re-sync only affects the vDev with the failed mirror device. Their are some writes to the other vDevs in a multi-vDev pool, in regards to critical metadata, but this would be minimal.


Well, actually yes and no.

Traditional resilvers have no idea where the data is, so they traverse the whole pool (or more recently specific TXGs). Of course, writes only affect the replacement device.

Sequential resilver, not to be confused with in-memory reordered resilver, does a straight copy from the old device to the new device. However, this provides few integrity guarantees, so it is automatically followed by a traditional scrub to ensure that everything was written correctly. So it’s not any faster overall, just faster getting to the point when the new device holds the data.