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Peak Usage
While your average bandwidth usage may be low, your peak usage is often many
times higher. Summary show both of these in the Overview : Bandwidth report with
a suggestion for what your connection speed should be. It is important that your
connection speed is large enough to accomodate the times of peak usage on your
site. When many users access your site simultaneously they each get a portion of
your available bandwidth. The fastest connections are slowed down by the other
connections happening at the same time. When the site is very busy, the
available bandwidth for the user with the fastest connection may be
significantly slower and your visitors will notice this. For example, if three
users come to a page at one time and each is downloading six images, that is 18
simulataneous connections. If another users is downloading at the same time, she
will only get 1/19 of your available
bandwidth. If your server has a 1 MBPS connection, that means each user is
getting 56 kbps. That is about the same as a good analog modem. If these users
all have a DSL line or a cable modem, they will be used to connections ten to
twenty times faster. Imagine how much worse it would get if you have six or
eight people connecting at once.
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Bandwidth speeds are measured in bits-per-second (BPS), while usage is
measured in bytes. In Summary’s calculations there are nine bits per byte,
so when comparing the number of bytes transferred to the average BPS, you need
to multiply by a factor of nine. For example, if your average bytes per day is
177 million then your average BPS would be about 18,438: 177,000,000 / 86,400
seconds per day * 9. These units are common practice, so your reports should
correspond to rates and values you get from your provider without any
conversions. (The actual number of bits per byte varies depending on the
transmission line so there may be a difference of exactly +/- 11%.)
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Figure 3. Find your most active hours
in the Peak Hourly Bandwidth report. |
In addition to the Overview reports, Summary provides several other reports
to help you determining peak bandwidth usage on your site. The Peak Hourly Bandwidth report, Figure 3, show the one-hour
periods that had the largest number of bytes transfered. The top few items on
this list show you what your peak usage, in the BPS column, was over all time.
The Peak Daily Bandwidth report gives similar
information for the most active days on your site.
Reducing Peak Usage
In the previous section we discussed Summary’s suggested bandwidth, which is
based on your peak usage. Rather than increase your available bandwidth (if
it is less than the recommended), you can try to manage the bandwidth usage on
your site by analyzing the cause of peak usage and compensating for that.
If these peak hours or days correspond to promotions that you are running on
your site, whether an email campaign, radio or television advertisement or
other marketing tool, you can reduce the peak usage by carefully managing the
campaign. If you spread out the campaign over a longer period of time, you can
spread out the hits and reduce the load on your server for that short time. For
example, if you run an email campaign for a new product release, and
simultaneously announce it on several product news sites, you could run the
email campaign the week before you release your announcement (perhaps as a
“pre-order” special for existing customers), and even spread out the
email campaign over several days.
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Figure 4. Find bandwidth-consuming
files with the Requests by Bytes report. |
Sometimes you cannot control the volume of requests. In that case, you may be
able to control the size of them to help reduce peak usage. The Requests by Bytes report, Figure 4, and the Directories by Bytes report can help you diagnose which
files or parts of your site are consuming the most bandwidth. Requests by Bytes
shows the total number of bytes consumed by each file on your site, ranked by
percent of recent bytes. So the top few items on the list are those that are
currently the largest load. Where possible, you could reduce the size of these
files.
Using the Directories by Bytes report, you can make similar adjustments
for directories (or sections) of your site that are affecting your peak usage.
If one directory is significantly higher than others, you can look at the files
in that directory and try to reduce the size, where possible.
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| Figure 5. Discover which media consumes
bandwidth with the Bytes by File Types report. |
Sometimes, it is not particular files or directories that consume bandwidth
but particular types of files. The Bytes by File Type
report in Figure 5 shows the top ranking media by byte. If you have
downloadable content, such as software programs or documentation, you can expect
these to rank highly. Graphics file types (gif, jpg, png, etc) will also have a
large percent of bytes. If you have audio or video content, these could be very
consumptive. Often, with graphics, audio and video, you can adjust the
compression level to reduce the size of the files (at the loss of some
quality.)
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Suggested Bandwidth