[DRBD-user] drbd Performance

Lars Marowsky-Bree lmb at suse.de
Wed Jul 16 19:12:56 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.

On 2008-07-16T12:05:53, nathan at robotics.net wrote:

>> You're being hit by the internal metadata. Putting the metadata on
>> another spindle will make it quite fast.
> What is the metadata overhead in DRBD? I am seeing about 100 MB/s overhead 
> with DRBD:

It's writing to the activity log when you dirty a new block; that costs
you latency, because the head has to move from the data area to the
metadata block.

And the latency indirectly affects the bandwidth you get.

Putting the metadata on a different, independent avoids this. SSDs are
really cool for this, as the metadata is also very small (just 128MB per


Teamlead Kernel, SuSE Labs, Research and Development
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde

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