On 03/10/2018 03:29 PM, Christoph Anton Mitterer wrote: > On Sat, 2018-03-10 at 14:04 +0200, Nikolay Borisov wrote: >> So for OLTP workloads you definitely want nodatacow enabled, bear in >> mind this also disables crc checksumming, but your db engine should >> already have such functionality implemented in it. > > Unlike repeated claims made here on the list and other places... I > woudln't now *any* DB system which actually does this per default and > or in a way that would be comparable to filesystem lvl checksumming. > I agree with you, also nobody warn that without checksum in case of RAID filesystem BTRFS is not capable anymore to check if a stripe is correct or not > > Look back in the archives... when I've asked several times for > checksumming support *with* nodatacow, I evaluated the existing status > for the big ones (postgres,mysql,sqlite,bdb)... and all of them had > this either not enabled per default, not at all, or requiring special > support for the program using the DB. > > > Similar btw: no single VM image type I've evaluated back then had any > form of checksumming integrated. > > > Still, one of the major deficiencies (not in comparison to other fs, > but in comparison to how it should be) of btrfs unfortunately :-( COW is needed to properly checksum the data. Otherwise is not possible to ensure the coherency between data and checksum (however I have to point out that BTRFS fails even in this case [*]). We could rearrange this sentence, saying that: if you want checksum, you need COW... > > > Cheers, > Chris. > -- > 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 > [*] https://www.spinics.net/lists/linux-btrfs/msg69185.html -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- 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
