[DRBD-user] Question about no-disk-flushes, no-md-flushes

Matthias Weigel matthias.weigel at maweos.de
Thu Aug 14 15:20:28 CEST 2008

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

Hello Lars,

so these options do not remove flushes from upper layers, but only 
control additional, drbd-internal flushes?

Best Regards


Lars Ellenberg schrieb:
> On Thu, Aug 14, 2008 at 11:23:39AM +0200, Matthias Weigel wrote:
>> Hello,
>> where exactly do disk flushes happen without this option?
>> - per IO?
> "disk-flushes" per drbd-barrier, which in turn are inserted between
> reorder-domains to keep write ordering on the nodes in proper order.
> "md-flushes" for every meta data access, i.e. al update or bm update.
>> With no-disk-flushes and no-md-flushes active, does a flush happen,
>> when  i say "sync"?
> different concept.
> different levels of "flush".
> so, the answer is "no", but probably the
> answer to what you mean would actually be yes.
> sorry, this is not easily put into two sentences.

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