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[kpmedia]

VPS for Wordpress? PHP memory limit?

If I have a two sites that, combined, get about 125,000 page views monthly (that comes out to about 4,000 page views daily). The sites are powered by Wordpress, and it is being used as a CMS, it's not a blog. There are a number of plug-ins in use, on each site, about 10 or so. Each site also has a vBulletin forum in use, although there are rarely more than 10 concurrent connections, if even that many (total of 400 members, only 150 of which are active -- combined stats for both sites).
Currently the PHP memory limit is set to 16M. I'm wondering how high it could or SHOULD go? Granted, I would not want to ask for more than what is available. Would the site speed improve if it was upped to say 128M? Let's pretend that I have a 512MB VPS SLM (no burst). It would have Linux+Apache+Plesk.
Is that enough of a VPS? Would I need to go to 640MB, 768MB, or even 1GB of RAM? Budget is an issue, so "yeah sure, go larger" is not an easy decision. It's also stupid to buy what's not actually needed. Maybe 256MB-384MB would be good enough?
Now then, what if I wanted to use this on a Windows IIS6 system instead? Let's say that I decided to add an ASP.NET wiki or blog to one of the sites. Clearly, that would demand more RAM, and I think Windows itself likes to eat more RAM. The Windows box would also have either Plesk 8.6 or Plesk 9. What's the difference in base RAM use that should be accounted for?
Virtuozzo is desired for either solution, be it Linux or Windows.
My current situation is shared, Windows 2003 Plesk, for these particular sites, and these two specific sites are loading really slow sometimes. Other times I get partial loads, error 500, or pure "unavailable" issues. Other sites, same machine, just fine. Even the vBulletin forums on the same domains load okay and fast, but the Wordpress sites crawl. It is IIS6, so use of WP-Cache/etc is pretty much impossible. I tried another cache, and it works -- but only for maybe 2 hours at a time, then something happens to it, and the cache quits. It's enabled, but it just stops functioning properly.
My shortlist of the moment includes KickassVPS, FutureHosting, and EuroVPS, for whatever new VPS plan that needs to be gotten. I've been watching the VPS offers threads for the past two weeks. I'm leaning hard to FutureHosting, for this one project, because of the Seattle NOC, since one of the site admins is close geographically, and he always has trouble with the current site's location (other side of the globe, for him).
I'm hoping some of the WHT experts have some good answers for this. I've been researching this for a while, both on WHT and off, but I can't seem to get a clear answer from reading alone. I need advice.
Thanks.





__________________Currently using: Windows 2008 + Plesk 8 (Dedicated), Windows 2003 + Plesk 8 (Shared), Linux Cent OS + Plesk 9 (VPS)Looking for a good host? Consider EuroVPS.com (paying customer for almost 3 years, and quite satisfied)

[vx|brian]

The memory limit set in PHP itself is just a limit, it won't affect performance at all on the server unless you're getting "Out of memory" errors, in that case you need to put it up.
I'd recommend Linux over Windows for a VPS as Linux takes much less resources, no licensing fees and usually scripts (PHP ones) work much better on Linux, about the ASP.NET wiki, there are plenty of other choices with a lot of features for Wiki's.





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[kpmedia]

Windows licensing costs are an understood, I use a dedicated 2008 IIS7 machine, as well as a 2003 VPS -- I don't admin those, I just maintain site design/content on those. But I'm aware of costs, and can accept it. That's a non-issue.
What exactly are the resource differences going to be on Windows vs Linux, for VPS? Are we talking 128M, 256M, something smaller, larger? I can't seem to find any side-by-side numbers, that would tell me "if you go Windows you'll need to account for -/+ _____ MB of RAM". Clearly, it would be a scenario-by-scenario comparison, but I can't find anything that would even allow me to extrapolate an educated guess.
What sort of memory would be suggested for the sites I have mentioned? What I really seek here is guidance on which VPS package would be the best choice, in terms of RAM needed, given the Wordpress/vBulletin/OS/Plesk/Virtuozzo combination of scripting/software that powers the site.





__________________Currently using: Windows 2008 + Plesk 8 (Dedicated), Windows 2003 + Plesk 8 (Shared), Linux Cent OS + Plesk 9 (VPS)Looking for a good host? Consider EuroVPS.com (paying customer for almost 3 years, and quite satisfied)

I can't speak much about Windows since I'm a Linux guy, but 4K daily pageviews on a Wordpress install isn't a huge deal. That's a handful of requests per minute at peak.
Why not take a close, hard look at your current memory usage? Which processes are the resource hogs? Is there a specific poorly-coded plugin doing something stupid/wasteful? Also, what about your database? How's your network?
Looking "under the hood" should help you get a handle on exactly how much resources you need. It sure helps to know exactly which components of your setup are consuming which resources. You'll probably even get some ideas to improve efficiency. Either way, this knowledge will help you make an informed decision. You'll stay on budget by buying exactly what you need.
Even if you have the cash to throw more RAM/CPU at performance problems, it always helps to keep an eye on resource usage.





Last edited by bcurve : 12-25-2008 at 08:00 PM.

[kpmedia]

Being shared on those sites, I don't have access (I don't think, at least) to know what the current usage is. I could be wrong, so correct me if that's the case.
I don't think any of the plug-ins in use are poorly coded or abusive to resources in any way. I've studied it a bit in recent months. My knowledge only goes so far, so getting under the hood may not be possible, due to access first, and knowledge second. Moving to a VPS, learning more would be a goal. The problem is trying to guess at which package to buy.
I was hoping somebody (smarter than I am, in these matters) could say "yes, I run a site with similar specs and I use ___ MB package VPS, and it works well". And then maybe even "I have room to grow" or "I'd have to upgrade if the site grew". I need numbers, a guestimate based off what I am able to provide thus far.





__________________Currently using: Windows 2008 + Plesk 8 (Dedicated), Windows 2003 + Plesk 8 (Shared), Linux Cent OS + Plesk 9 (VPS)Looking for a good host? Consider EuroVPS.com (paying customer for almost 3 years, and quite satisfied)

[Whoa]

I an running three small sites (two wordpress blogs and a SMF forum), that receive ... say about half the traffic you're getting right now.
All running happily on a VPS with 256MB RAM(512MB burstable).
My installation? The two wordpress blogs receive low traffic - I've allocated them three dedicated fastcgi php processes each.
The SMF forum gets a bit more traffic - it gets 4 processes.
On my VPS each php process can serve about 5-10 requests per second (almost twice as many in case of SMF). Which mean, with the three processes running, thirty users can be online - each getting a new wordpress page served every second.
This is a safety factor of more than 20, in my case.
The Apache2 installation is set to serve 128 concurrent connections.
My current idle RAM usage is 114MB for Apache2 + php5 + mysql5 + proFTPd + postfix + courier (pop+imap) + BIND, serving those three sites + ISPCP control panel. Each php process being served is a transient load of about 12MB.
In 1.5 years, I've never ran into my bustable memory allocation.
If a website gets slashdotted, I have wordpress cache plugin ready. It can drastically reduce server load in such cases.
By the way, only yesterday I was experimenting with LiteSpeed webserver standard edition + php lsapi.
I'm highly impressed with this web server.
The php execution times for all scripts were cut down to 2/3 compared to apache2+phpfastcgi. With 5 php processes running, idle RAM usage was 60 MB.
However, I'm back to running Apache2 at the moment as I couldn't figure out how to get my webmail script working with it (probably a php compilation issue).
p.s. - All that was my own calculations. I do not make any claims as to my understanding of these things. If someone knows better ... please correct.
Edit - I'm running Linux on my VPS, by the way





Last edited by Whoa : 12-26-2008 at 05:21 AM.
Reason: forgot to add VPS OS

[kpmedia]

Thank you for giving some numbers that I can ponder.
Anybody else?





__________________Currently using: Windows 2008 + Plesk 8 (Dedicated), Windows 2003 + Plesk 8 (Shared), Linux Cent OS + Plesk 9 (VPS)Looking for a good host? Consider EuroVPS.com (paying customer for almost 3 years, and quite satisfied)

Good to see you have some numbers. Note that the poster was a Linux guy, so I'm not sure how relevant a comparison his setup is to your Windows situation.
On a shared host, you may be able to get some stats. Most of the "canned" hosting apps come with control panels that at least provide some data. Maybe there's a way to connect/remote in (I'm not sure how it works in Windows land)?
Also, don't rule out just asking your host for more info in a support ticket. As long as their support isn't worthless, I imagine that you're likely to get a good answer if you mention performance issues and that you're trying to get a handle on your resource usage.