UBB.threads PHP Forum Software Community Forums General Off Topic RE: http://www.mindraven.com/blog/linu x/speed-up-your-ext3-filesystem/

I see what you're doing Rick, and it is a cheap way to milk the last drips of performance out, but man I'd be lost with noatime set. I think if I were that tight on I/O headroom I'd have to consider a physical upgrade before I'd run with noatime. On the occasion where something breaks (something always does) and you need to figure out when and how you're giving up a pretty good tool that you could use to help investigate. I view it as a pay me now or pay me later decision. I guess it depends on the position you're in and your risk assessment. For some running noatime doesn't pose much risk, but for me I'd view it as a large risk.

Definitely food for thought. Nice post.

what tools do you use that rely on atime, just out of curiosity? I've been running production servers for the past 6 or 7 years and always add that flag on any server that does a lot of reads. Have never ran into an issue on any server problems that required last access time on files.

By tool I mean the access date/time stamping. Beyond that it's my peepers.

Typical usage:

"hey what happened to ...., it was fine this morning, but it just had a melt down?"

"config file was last modified xx/xx/xx at xx o'clock. Who was working then?"

Or, as we unfortunately have seen in the past far too often:

support ticket - Hello, I've been getting a lot of email bounces for emails I haven't sent, can you tell me what's going on? It's been happening since Saturday.

A quick ls sorted by date reveals that the client's handy dandy php ad rotator or perl mailing system has been altered on Saturday. Or that there is a new file named a.pl dated that Saturday which upon examination turns out to be a perl based shell that was uploaded through an old phpmyadmin exploit.

These are things that would strike me as slower to do with atime off.

Again, your own site's rick assessment will determine whether this is an issue or not. If you are the only one that ever touches your files it might not be much of an issue at all. As someone that spends a lot of time finding, cleaning up, then explaining various messes I find it pretty indispensable.

Ahh. Actually with atime off if a file is modified it still has the modification date. If someone modified a config file, it's still going to have the modification time. If a php script was modified, it's still going to have the modification time.

The only thing noatime does is it gets rid of the access time update. As it stands, with atime on, every time a file is read (mot modified), the access time is updated. That really isn't that useful to anything except for a few programs that actually rely on it still.

So, you can safely run with noatime on and still be able to see when files were actually modified I should modify the blog post to note that.

In a recent discussion about atime that involved Linus Torvalds, this pretty much summed it up.

Good points and I, apparently, had a mistaken understanding of it. I need to go read up!

+1 Rick
-1 Dave

:X

No the first time, certainly not the last.

t*

i'm just mesmerized by David's sig...

that is all...

damn sirdude I was just slammed by your sig dang it... I thought the cat was chasing my cursor for a minute...

You suck LOL


Dunny