Re: For a FFS on an SSD, which of "-o" nil, "sync" &/ "softdep" is more data-safe and fast?

Also use noatime mount option so whe reading files you are not updating
access time

On 8 Feb 2018 7:36 PM, "Tinker" <t1nkr@protonmail.ch> wrote:

> Hi!
>
> If I understand mount(8) (http://man.openbsd.org/mount) right, FFS
> mounts have a metadata I/O mode and a data I/O mode. By default,
> metadata is accessed synchronously and data is accessed
> asynchronously.
>
> "-o sync" will force both to synchronous mode, and "-o softdep" would
> change the metadata I/O mode to the alternative softdep access mode.
>
>
> What is the optimal sync &/ softdep configuration for minimizing risk
> of data loss on unexpected reboot, and maximizing overall filesystem
> I/O speed?
>
> By "data loss" I mean in particular filesystem structure issues that
> could cause fsck(8) hickups and stability issues (e.g. the "/var/log"
> directory disappearing altogether - I've seen that happen), secondarily
> that file data content updates not would have stuck on the disk.
>
> Either nothing (no "-o" setting), or "-o sync,softdep", or "-o sync",
> would all look like they'd make sense.
>
> (Can you even do "-o sync,softdep", would that serve any purpose?)
>
> Will appreciate to learn your thoughts on this one a lot,
>
> Thanks,
> Tinker
>
>