You mean permanently deprivating your server of it's precious ram than
only temporarily? And so far, swapping has always been the worst thing
to happen for me - whereas mere disk-IO didn't slow _everything_ down.
You should really check your premises on what is affecting performance,
and what not. And get a faster server...
Diez
What resources this server is lacking currently?
Harddisk space
Harddisk bandwidth (the server just wouldn't stop reading/writing at
peak times)
RAM
Network
CPU
In short, what resource is the most precious and what resources you
still have spares?
Possible option:
* Serve the PDFs directly
--> Harddisk space - low, as it's not converted
--> Harddisk bandwidth - low, depends on how much its requested
--> RAM - low, virtually no RAM usage
--> Network - low, depends on how much its requested
--> CPU - low, virtually no processing is done
--> The simplest to implement, moderate difficulty for users that
don't have PDF reader
--> Users that don't have a PDF reader might experience difficulties,
nowadays most people have Adobe Reader on their computer, and most
people at least know about it. Many computers are also preinstalled
with a pdf reader.
* Preconvert to PNGs, the conversion is done at another computer to
not restrain the server
--> Harddisk space - High, as file is saved as image file
--> Harddisk bandwidth - Moderate, as there are many files and overall
are big
--> RAM - low, virtually no RAM usage
--> Network - Moderate, as the total file served is big
--> CPU - Low, virtually no processing is done
--> Simple
* Serve a precompressed, preconverted PNGs
--> Harddisk space - Moderate-high, should be smaller than just PNG
--> Harddisk bandwidth - Moderate-High, as files can't be served in
chunks
--> RAM - Low, Virtually no RAM usage
--> Network - High, as files can't be served in chunks
--> CPU - Low, virtually no processing is done
--> Moderately-Simple
--> Might be problem if users don't have unzipper (XP, Vista, and most
Linux provides unzipper on default installation, older OSes might not)
--> Files can't be served in chunks, users have to download whole zip
before opening any
* Convert the PDFs to PNG on the fly:
--> Harddisk space - Low, take as much as serving direct PDF
--> Harddisk bandwidth - Moderate to Low, depending on implementation
--> RAM - Moderate, as processing is done, RAM is clearly needed
--> Network - Moderate, as the files served as PNG
--> CPU - High, complex processing is done on the CPU before the file
can be sent to the network
--> Complex to implement
Seeing these options, I think it is much better to serve the PDFs
directly, it's very simple, and very efficient on the server. If
you're afraid that not everyone have PDF readers, direct them to
Adobe's site or serve the installation files on the server. The
installation for the reader is a one-off download, so it should only
choke the server for the first several weeks.
