[rrd-users] Neuro data in RRD - ns time steps?

Tobias Oetiker tobi at oetiker.ch
Tue Aug 28 22:20:10 CEST 2007

Hi Peter,

changeing to a different base unit for time should not be all that
much of a problem as long as you do not aim for compatibilityy ...
note that you will have todo something about the labeling code in
the graphs and you will have to come up with a way to store the
time counter ... as long as you sample for a short periode, this is
no problem but if yo waim for pico second resolution over a 1000
years, you may have to do something more sophisticated ...


 apart from that it should be fairly simple ...

> Hi All,
> I'm an academic neuroscientist who is looking for an efficient way to store
> and retrieve recorded neuronal data for use in an intranet data browser app.
> After an initial read through the documentation and tutorials, RRD seems to be
> very close to what I had been thinking of with one exception, our data is
> recorded at 5-25KHz, so we need time steps of 50-200 nanoseconds. So I am
> wondering... has anyone modified RRD to work with smaller time steps? If not,
> I am curious about how much coding would be required to do this (i.e. how
> deeply embedded is the time structure currently used in the database)
> My alternatives would be to use a BLOB system in MySQL, or just use file
> references in a database and build a custom system to scan the binary data
> files and return the requested chunks.  So I would also be curious if anyone
> has any opinions (performance, scalability, etc.) of different ways of
> building time series data browsers.
> By the way, our files are large - each experiment is recorded on 60 channels
> for 2 hours, which we break into consecutive 2 minute files(~ 70Mb for a 5Khz
> recording) for ease of use. I would ideally like to have an RRD for each 2
> hour experiment, with each channel as one GAUGE DS containing 36-180M data
> points (in the native format theses are 2 byte unsigned integers). Are these
> sorts of numbers worrisome in terms of performance?
> Thanks,
> Peter
> Peter Passaro
> Research Officer
> Dept of Informatics/Dept of Biology
> Pevensey III
> University of Sussex
> Falmer, Brighton BN1 9QH, UK
> Office + 44 (0)1273 877590
> P.A.Passaro at sussex.ac.uk

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten
http://it.oetiker.ch tobi at oetiker.ch ++41 62 213 9902

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