Askemos Accuracy Test
About the Test
Here we compute some statistics on the accuracy of the
Askemos network.
Accuracy is approximately the equivalent of "uptime"
for physical computers.
Within the network we have two types of availability:
- locally available / read available
- Data can be read, and modified on a single machine, but modification with respect to replica synchrony is not checked.
- replica synchrony / write available
- A replicated transaction was performed under non-repudiation protocol.
Since we run from the same basic hardware and - for the most part - software setup as most web services (PC's loaded with Linux or FreeBSD) average read availability is a fixed value of about 99.999% (less than 5 minutes a year of downtime).
Test Setup
To measure replica synchrony,
each node in the network is configured to send
a local, public write message with it's idea of current time
to it's replica of
Here in turn we run the agreement protocol again to count how many minutes passed since the last agreed-on time tick. Furthermore we count the missing minutes as errors.
Interpretation
The whole test amounts to two runs of the protocol, which both fail with a certain probability for a variety of reasons like network latency, messages drops, delays from data base access, software updates, broken hardware etc. The time out of 5 seconds is actually sometimes hard to meet for the WAN test setup, though on average we have less than 0.3 seconds per agreement over SSL. The logfile confirms, that messages arrive as late as 20 seconds past the full minute.
The reason for the low availability measured here is that we measure the test network, which has downtime due to bugs.
The average accuracy is with atotal total number of agreements (failed and successful) and afailure number of failures roughly[1]:
Results
| Current Time |
|
|---|---|
| Checked Time |
|
| Failure Count |
|
| Accuracy |
Source
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