Echelon i.LON 100 e2 Internet Server - Manual (Page 71)

i.LON 100 Internet Server User’s Guide 5-5
It should be noted that the block erase limit specified by the flash manufacturers
is very conservative. Empirical testing of at least some flash parts indicates that
a typical limit under normal conditions may be at least 10 times longer, which
translates to a much longer life for the i.LON 100 flash disk, and/or erase rates
much greater than 39 erases per minute. Informally, flash manufacturers will
confirm these findings, but they cannot be guaranteed. Use this information with
caution, depending on how conservative you wish to be. You may also trade off
expected lifespan for increased erase rates.
The configuration of your i.LON 100 may have a significant impact on the
number of flash erases per minute. Because of this, it is important that you
monitor both the rate at which you are erasing the flash blocks on your i.LON
100, and how many spare disk blocks are available. You can do so using the
information on this Web page. If the number of spare block falls below the
recommended minimum, you should consider replacing the i.LON 100.
The rate of flash block erases is a difficult number to report. Short-term increases
or decreases in this value are not meaningful to the lifespan of the flash. Only
long-term, sustained rates are truly significant. However, if you are trying to
adjust your data logging to see what affect this has on the erase rate, a long-term
number is not very helpful. To accommodate these different needs, this Web page
reports four different values for the flash block erase rate.
The most important one is computed using a two-day moving average, which will
reflect only sustained erase rates. However, this average is slow to respond to
changes in the rate, and it may take up to five days before the value fully reflects
a sustained change in the erase rate. The three minute and one hour values
provide more immediate feedback by using shorter time windows, but they may
show jumps in their values due to short-term activity (for example, transferring a
file via FTP to the i.LON 100). The final value is the rate since the last reboot,
which may respond to rate changes even slower than the two-day average, but
provides a very long-term view.
The following parameters are displayed on this Web page:
Flash Disk Activity:
Moving Average
The long term moving average of the number of flash
block erases/minute (using a two day sliding
window). When this value exceeds the recommended
limit of 39 erases/minute, the value will be shown in
red and a warning message will be displayed at the
top of the web page.
Flash Disk Activity: Last
3 Minutes
The number of flash disk erases/minute over the last
3 minutes.
Flash Disk Activity: Last
1 Hour
The number of flash disk erases/minute over the last
1 hour.
Flash Disk Activity:
Since Startup (<Time
Since Startup>)
The number of flash disk erases/minute since the
i.LON 100 was last rebooted.
Spare Flash Blocks The number of available spare flash blocks
remaining out of the 46 total. Initially, the i.LON
100 contains up to 46 spare flash blocks that are
used to accommodate block failures. However, it is
normal for a small number of flash blocks to initially
be marked as failed by the flash manufacturer, and
additional blocks may fail after extended use, so the