Lately my server company has a habit of creating this "virtual partition". They tell me it's a default thing done by the OS (CentOS 5). Thing is, I don't remember this being a default thing in my installations of CentOS 5.

From what I gather it's a virtual partition with the bonus of mounting as noexec and being resizable. Now I may be completely wrong in this, but it seems to me a physical partition would be faster. The last couple servers I've had I've requested a physical partition be made.

The last server I had done I asked for a /tmp partition but ended up with a /usr/tmpDSK type partition. Now the last time this happened I had them add a physical one, but before I do that, is it really necessary?

Are there any pros and cons I'm missing? Are my assumptions wrong? Is this something that is done by default? Or is this just a mistake by someone customizing the partition map wrong?

Thanks in advance!

Luke

It was perhaps created with a cpanel script rather than by the distro. It has security advantages.

I would be surprised if there was a measurable difference in speed. The small overhead of the loopback layer is going to be lost in the variation noise of any measurements you might make. It might even be slightly faster than a separate partition for /tmp, because the head seek times will be reduced.

If you are using some application that is speed bound by file access to /tmp (unlikely), then you would look at getting more memory (to provide more file caching space) or even create /tmp as a ram based filesystem.

But beware unSpawn that does not think it safe to delete files in /tmp at boot as would happen in it were RAM-based. See this LQ post and follow-ups.

From the tldp

"On most systems, this directory is cleared out at boot or at shutdown by the local system. The basis for this was historical precedent and common practice. However, it was not made a requirement because system administration is not within the scope of the FSSTND. For this reason people and programs must not assume that any files or directories in /tmp are preserved between invocations of the program. The reasoning behind this is for compliance with IEEE standard P1003.2 (POSIX, part 2)."

Thanks for the authoritative citation, neonsignal

I, too, favour and implement emptying /tmp on boot except for any lost+found directory, quota files and security files (not familiar with the last) but I respect unSpawn's opinion and experience.