I know nothing about "Time Machine", but does it copy the entire filesystem in (at least) "crash consistent" state?
--- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. >-----Original Message----- >From: sqlite-users [mailto:sqlite-users- >boun...@mailinglists.sqlite.org] On Behalf Of Daniel Alm >Sent: Tuesday, 11 December, 2018 05:02 >To: sqlite-users@mailinglists.sqlite.org >Subject: [sqlite] Mac: Users receive "database disk image is >malformed" errors after restoring database from Time Machine backup > >Hi, > >For the past half year we’ve been receiving reports from users who >had restored their SQLite-based databases from a Time Machine backup. >Afterwards, they would receive "database disk image is malformed” >errors. The app also backs up the user’s data “manually” to a ZIP >file every week; those backups seem to be working fine. We also >haven’t received reports from other backup tools causing issues. I >have also suspected a bug in Time Machine, but it is striking that >the issues did seem to start occurring after an update to the app >(luckily, in fact, with the same update that also introduced the >“manual” backups). > >Changes that we made to our setup in the update that coincided with >the errors occurring: >- Upgraded SQLite from 3.21 to 3.24 (we have since reverted to 3.23.1 >in another update; no improvement). >- Used memory mapping for read accesses via “PRAGMA mmap_size = >1073741824;” (we have since reverted to “PRAGMA mmap_size = 0;” after >reading http://sqlite.1065341.n5.nabble.com/Re-Database-corruption- >and-PRAGMA-fullfsync-on-macOS-td95366.html ><http://sqlite.1065341.n5.nabble.com/Re-Database-corruption-and- >PRAGMA-fullfsync-on-macOS-td95366.html>; no improvement). >- Using a secondary database via [ATTACH >DATABASE](https://www.sqlite.org/lang_attach.html ><https://www.sqlite.org/lang_attach.html>) (although this also seems >to occur for users without such a database). > >At this point, I am at a loss, especially given that SQLite should be >fairly robust against database corruption. While our app is running >in the background all the time, it is not very write-heavy (~ one >transaction per minute taking just a few milliseconds). Also, the app >had been running fine before the update for a long time without any >reports of this issue. I might be doing something wrong or have >changed anything else, but I don’t know what; if you have any ideas, >let me know. > >Any suggestions on what could be the culprit or what else I could try >besides downgrading all the way to SQLite 3.21 would be appreciated. > >Thanks, >Daniel Alm > >P.S.: Our database currently uses the following PRAGMAs: > >PRAGMA mmap_size = 0; >PRAGMA page_size = 4096; >PRAGMA cache_size = -10240; >PRAGMA foreign_keys = ON; >PRAGMA journal_size_limit = 8388608; >PRAGMA checkpoint_fullfsync = 1; >PRAGMA wal_autocheckpoint = 2048; >PRAGMA journal_mode = WAL; > >Happy to provide any more details as needed. >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
