Messages in this thread | | | From | Johannes Thumshirn <> | Subject | Re: [PATCH v4 08/13] btrfs:zoned: make sb for npo2 zone devices align with sb log offsets | Date | Tue, 17 May 2022 06:50:53 +0000 |
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On 16/05/2022 18:55, Pankaj Raghav wrote: > Superblocks for zoned devices are fixed as 2 zones at 0, 512GB and 4TB. > These are fixed at these locations so that recovery tools can reliably > retrieve the superblocks even if one of the mirror gets corrupted. > > power of 2 zone sizes align at these offsets irrespective of their > value but non power of 2 zone sizes will not align. > > To make sure the first zone at mirror 1 and mirror 2 align, write zero > operation is performed to move the write pointer of the first zone to > the expected offset. This operation is performed only after a zone reset > of the first zone, i.e., when the second zone that contains the sb is FULL.
Hi Pankaj, stupid question. Npo2 devices still have a zone size being a multiple of 4k don't they?
If not, we'd need to also have a tail padding of the superblock zones, in order to move the WP of these zones to the end, so the sb-log states match up.
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