On Thu, Jul 22, 2021 at 10:32:18PM +0000, Bossart, Nathan wrote: > On 7/6/21, 7:02 PM, "Gurjeet Singh" <gurj...@singh.im> wrote: > > I think it would be helpful if the help message was slightly more > > descriptive. Some options: > > > > Used in patch: > > only sync data directory; does not modify any data > > > > To match the wording of --sync-only option: > > write contents of data directory to disk; helpful after --no-sync option > > > > Clearly specify the system operation used for the option > > perform fsync on data directory; helpful after --no-sync option > > I think the help message should say exactly what the option does and > should avoid saying what it does not do or how it may be useful. I > would suggest the following to match the initdb docs [0]: > > -S, --sync-only safely write all database files to disk > and exit > > IMO the note about the option being helpful after using the --no-sync > option would fit better in the docs, but I'm struggling to think of a > use case for using --no-sync and then calling initdb again with > --sync-only. Why wouldn't you just leave out --no-sync the first > time?
It's to allow safely running bulk loading with fsync=off - if the bulk load fails, you can wipe out the partially-loaded cluster and start over. But then transitioning to a durable state requires not just setting fsync=on, which enables future fsync calls. It also requires syncing all dirty buffers. doc/src/sgml/config.sgml- <para> doc/src/sgml/config.sgml- For reliable recovery when changing <varname>fsync</varname> doc/src/sgml/config.sgml- off to on, it is necessary to force all modified buffers in the doc/src/sgml/config.sgml- kernel to durable storage. This can be done while the cluster doc/src/sgml/config.sgml- is shutdown or while <varname>fsync</varname> is on by running <command>initdb doc/src/sgml/config.sgml: --sync-only</command>, running <command>sync</command>, unmounting the doc/src/sgml/config.sgml- file system, or rebooting the server. doc/src/sgml/config.sgml- </para> -- Justin
