[DRBD-user] how long does drbd device do sync

Mark Watts m.watts at eris.qinetiq.com
Thu May 10 14:05:54 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


> > It can be one of the following three:
> >
> >    C: write IO is reported as completed, if we know it has
> >       reached _both_ local and remote DISK.
> >       * for critical transactional data.
>
>        * for most cases.

Most ?

> >    B: write IO is reported as completed, if it has reached
> >       local DISK and remote buffer cache.
>
>        * for cases were you can live with possible data loss
>          of the last few milliseconds in case of failover
>
> we should improve our documented recommendations :)
>
> >    A: write IO is reported as completed, if it has reached
> >       local DISK and local tcp send buffer. (see also sndbuf-size)
> >       * for high latency networks
> >
> > If you choose C, then write a file to the DRBD'd filesystem,
> > the write won't
>
> and then fsync! otherwise the write goes
> just into the local nodes cache,
> and drbd knows nothing about it yet...

Do you bypass this requirement my mounting your filesystem sync ?

Mark.

-- 
Mark Watts BSc RHCE MBCS
Senior Systems Engineer
QinetiQ Trusted Information Management
Trusted Solutions and Services Group
GPG Key: http://keyserver.veridis.com:11371/search?q=0x455420ED
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