Increasing write buffer size?

I can't follow exactly what do you want to do to achieve what (I can't think of any write buffers associated with drives in DC++) Elaborate your problem please to get better understanding.

And where can i change read buffer size?

I am running Airdc right now but under the advanced tab there's a box where i can change "write buffer size"

"Socket write buffer: The size of the buffer DC++ use to write to sockets. Measured in bytes. (default: 8192 bytes)"

Smaller value means the drive have to work harder, as what i have read about it on various sites and forums anyway. Could increasing this value to 128 kb would be of any good for my harddrive where i put my downloads to?

This is a buffer for network transfers and has nothing to do with disk I/O.
Your OS' disk cache is working on much larger scale than these numbers so I'm afraid your various forums are wrong. It won't have such effect at least not for DC++.
Not sure about AirDC though as it is heavily modified in several areas compared to DC++. You should ask this (and any other question regarding AirDC) in their support forum anyway.

..and "Socket write buffer size" is for the data leaving the client (uploads) so if you want to alter the networking buffer to effect the downloads then you should obiviously change "Socket read buffer size"...

Ooops! I typed wrong. What i meant was the

Write buffer size: This controls the size of the chunks that DC++ writes to disk for downloads. Measured in kibibytes. (default: 16 KiB)

Sorry!

http://dcplusplus.sourceforge.net/webhelp/settings_expert.html

There is the option for "Write buffer size".

Yup. Strange that I wasn't aware of that option... looking at the code it does what it says and increasing the buffer size is resonable if you have high speed downloads (e.g. in a LAN).

Increasing it would put less stress on the disk where i put my downloads to if i have a high speed connection? Currently AirDC++ put it default at 64 Kb. Dunno what the DC++ client set it too but i guess it's at 16 Kb?