DRBD performance question ?

[Ravi Wijayaratne]

Hi Phillip,

> 
> Right! In the "drbd_paper_for_NLUUG_2001.ps.gz"
> paper you will find the 
> following paragraph:
> 
>  4.1 Protocol A
>  Protocol A signals the completion of a write
> request as soon as we have
>  written the block to the local disk and sent it out
> to the network. We
>  signal the completion of the operation without
> knowing wether the block
>  has arrived or will arrive on the disk of the
> mirror.
>  ....
>  
> In case you write a stream of data that is
> considerabely larger than the
> memory of your machines, you have got these limiting
> factors for performance:
> 
> Protocol A:
> 1) Throughput & latency of your local disk
> 2) Throughput of your network connection
> 3) Throughput of your remote disk
> 
If in protocol A we signal I/O completion as soon
as we write to the local disk and the local network,
why would the write I/O performance of node 1
(primary) depend on the network throughput or the I/O
throughput of the remote disk ?

I apologise if I am missing something obvious ?

Thank you
Ravi

=====
------------------------------
Ravi Wijayaratne

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