Andrioid's questions

I have a rather old server that has 4GB of RAM and it is pretty much serving the same files all day, but it is doing so from the hard drive while 3GBs of RAM are "free".

Anyone who has ever tried running a ram-drive can witness that It's awesome in terms of speed. The memory usage of this system is usually never higher than 1GB/4GB so I want to know if there is a way to use that extra memory for something good.

• Is it possible to tell the filesystem to always serve certain files out of RAM?
• Are there any other methods I can use to improve file reading capabilities by use of RAM?

More specifically, I am not looking for a 'hack' here. I want file system calls to serve the files from RAM without needing to create a ram-drive and copy the files there manually. Or at least a script that does this for me.

Possible applications here are:

• Web servers with static files that get read alot
• Application servers with large libraries
• Desktop computers with too much RAM

Any ideas?

Edit:

• Found this very informative: The Linux Page Cache and pdflush
• As Zan pointed out, the memory isn't actually free. What I mean is that it's not being used by applications and I want to control what should be cached in memory.

I've worked as a sysadmin for some years and what I keep coming back to is that users like Microsoft Outlook and want to use its Exchange features. I have tried my fair share of commercial alternatives but usually there is either a fundamental feature missing or there are stability issues.

In short I am looking for a Microsoft Exchange Alternative with the following features:

• Authentication through SQL or LDAP
• Has a solid, comfortable web interface for the users when they are off-site
• Supports replication and load balancing (if one fails, the second one should be already running)
• Outlook client support (or a really good alternative client)
• Resource booking (meeting rooms, projectors, company jet, etc)
• Calendar (shared/private) and Email (if that wasn't obvious)
• (Optional) A cross-platform client for us *nix users.
• (Optional) Corporate support contracts available
• (Optional) An open-source software is a plus

Please keep your answers as detailed as possible to determine that you've successfully deployed the software and it fulfills the needs. If I wanted a list of claimed alternatives , I would simply Google it.

I've personally tried Binary Server, Novell Groupwise, homegrown Postfix/Cyrus stuff and in the end the 'real thing' because those users just love Exchange.

Please help me find a good alternative.

I have a 500G SATA hard drive in my machine that all the sudden started giving me I/O errors, until Linux simply disconnects the drive. Reboot, and then it works for a random period before failing again.

The drive is within warranty, but I've had bad experience with shops that are unable to reproduce a problem, as the drive doesn't fail all the time. Then they simply send me a bill and the drive back.

What is my best course of action to make sure they can reproduce the problem?

Update: Those of you who have recommended the diagnosis tools, it's a good valid answer, expect as stated in my question, I'm running Linux and these tools do not exist for it. As for 'gaming' the store, it's not about that. The drive is well on its way of being completely unusable without any help from me. I'm just talking about speeding up the process.

Update 2: I don't really know why I decided to ask this here. I was hoping for suggestions like 'do a badsector test', 'try to stress the drive with copying random data to it with dd'. I will say this again, so stop suggesting it or suggesting me not to... I will not in any way terminate my warranty by messing with the hardware itself, that includes; bulk erasers, huge magnets, too much power or anything that will show up when the drive is eventually sent back to the manufacturer.