[DRBD-user] Which is better, internal or external meta data?

Motoharu Kubo mkubo at 3ware.co.jp
Thu Feb 24 12:25:31 CET 2011

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


Hi Ikeda-san,

> I know this performance disadvantage is really rare case,
> so I would like to recommend "internal meta data" as the community
> recommended value.

I absolutely agree with you.

Consideing buffer or cache on storage device or RAID controller, and
considering metadata size (approx. 1/32768 of data area size),
performance issue can be ignored for most cases.

The almost only situation that external metadata is required is to add
DRBD redundancy to an existing filesystem with various limitation
described in the Users Guide.

If high availability is the most important issue, we should avoid using
older hardware as possible as we can.  In addition, people often want
not only high availability but also larger storage space and/or higher
performance.  I have never experienced the necessity of external
metadata in my several years experience.

I hope my tiny opinion helps.

Thanks,
Motoharu Kubo



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