On 05/23/2018 11:09 AM, Duncan wrote: > ein posted on Wed, 23 May 2018 10:03:52 +0200 as excerpted: > >>> IMHO the best course of action would be to disable checksumming for you >>> vm files. >> >> Do you mean '-o nodatasum' mount flag? Is it possible to disable >> checksumming for singe file by setting some magical chattr? Google >> thinks it's not possible to disable csums for a single file. > > You can use nocow (-C), but of course that has other restrictions (like > setting it on the files when they're zero-length, easiest done for > existing data by setting it on the containing dir and copying files (no > reflink) in) as well as the nocow effects, and nocow becomes cow1 after a > snapshot (which locks the existing copy in place so changes written to a > block /must/ be written elsewhere, thus the cow1, aka cow the first time > written after the snapshot but retain the nocow for repeated writes > between snapshots). > > But if you're disabling checksumming anyway, nocow's likely the way to go. Disabling checksumming only may be a way to go - we live without it every day. But nocow @ VM files defeats whole purpose of using BTRFS for me, even with huge performance penalty - backup reasons - I mean few snapshots (20-30), send & receive. -- PGP Public Key (RSA/4096b): ID: 0xF2C6EA10 SHA-1: 51DA 40EE 832A 0572 5AD8 B3C0 7AFF 69E1 F2C6 EA10 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
