[rrd-developers] interleaving RRD files, RRDfs perhaps?

[Daniel.Pocock at barclayscapital.com]

With a system such as Ganglia, there are many RRD files all created with
exactly the same parameters.

While rrdcached provides benefits by caching updates to each file, we
still see lots of small 4kb random access writes to the SAN.

Has anyone considered the possibility of aggregating multiple RRD files
with identical RRAs into a single file, or even some kind of
pseudo-filesystem?  This would mean that each disk block would contain
data from many RRDs common to a specific update time.  There would be a
dramatic improvement in write speed, as the OS and SAN would be caching
the blocks relating to the current time period, rather than racing back
and forth all over the disk.

It would be particularly desirable to be able to tune the block size
used for interleaving, so that it could maximise filesystem and SAN
performance.

Regards,

Daniel
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