Profiles

I'm about to move a big site over from Dreamhost. It gets anywhere from 30,000 to 250,000 pageviews a day.

Over at DH, it's using 500 megs to 2 gigs with their bloated build of apache. I figure I can expect a lot less with this setup (lighttpd), but I'm unsure.

I'm on a 540 right now, and I'm thinking about getting a 1440 for the the first month of the big site, in case I need it, and then downgrading if I can get away with it.

My question is: can I just move the OS disk image over to a different linode, or will I need to redo the whole distro and everything from scratch each time?

I assume I can move my site/db images no problem. (I have them separate from the os image)

7 Replies

Migrations are pretty quick and easy, as long as there's availability in your given datacenter. Open a ticket wanting to downgrade (or upgrade), and you'll get a big ol' "Migrate" button. Shut down, click that, wait a number of minutes (pessimistically, 2-3 minutes per GB), then start it back up. On a downgrade, you'll receive a pro-rated credit.

It's a good idea to resize your disk images to a more compact size before migrating, even more so if you're migrating to a lower plan. It'll make the actual migration faster, and fitting your data onto a smaller linode will be easier :-)

Cool, that's good to hear. Is it foolproof? Like, are they all the same hardware or something? How can you just move an OS to a new box with no problems? Magic?

From Linode's perspective, your disk images are just big files. A migration consists of copying your images and configuration over, which is pretty easy. Your system is blissfully unaware that anything changed, since its soul is contained entirely within those files. :-)

I don't think you need a 1440 at all. Dreamhost's Apache setup is ridiculously bloated. If you're using 500M-2G of RAM on Dreamhost, you can probably make do with less than half of it on Linode. And of course, switching to either lighttpd or nginx will save you even more RAM (and consequently $$ as well).

250,000 pageviews per day = 3 pageviews per second.

I have a forum on lighttpd + PHP + MySQL that can handle at least 30 and up to 80 requests per second (according to ApacheBench) when used with proper caching. Of course that's CPU bound. But the point is that my RAM usage remains below 200M all the time.

> 250,000 pageviews per day = 3 pageviews per second.

True, but on big days like that, I get my traffic through Digg, so it's concentrated mostly on a short period of time. I think I'll start on the 1440 just to be safe.

I'll set the test site up on lighty and nuke the hell out of with ab.

On a related note, is there anything better than ab? It seems to timeout sometimes for no reason, even on -n 1 -c 1. The problem is not in the site, I am sure.

> From Linode's perspective, your disk images are just big files. A migration consists of copying your images and configuration over, which is pretty easy. Your system is blissfully unaware that anything changed, since its soul is contained entirely within those files.

Right. So, since it's virtualized, does that mean the OS is just seeing generic hardware, regardless of the physical setup? I believe you about the migration, but my knowledge in this area is pretty shakey.

@Driscoll:

Right. So, since it's virtualized, does that mean the OS is just seeing generic hardware, regardless of the physical setup? I believe you about the migration, but my knowledge in this area is pretty shakey.

When it comes down to the actual instruction set, there's practically no difference between the various Intel processors. I can compile a binary on my home Linux box (a crappy Dell PC I found on the curb) and run it on my Linode, and vice versa. The "genericness" of the IA-32 and Intel 64 platforms means you can (with some creativity and effort) move images between VPS providers and even onto/off of "real" hardware with some minor configuration file tweaks. -rt

@Driscoll:

Right. So, since it's virtualized, does that mean the OS is just seeing generic hardware, regardless of the physical setup? I believe you about the migration, but my knowledge in this area is pretty shakey.

The OS, meaning the kernel itself, is the only piece of software that really deals with hardware. And it's nothing but a program that runs on the host. All your apps and data don't care in the least, as long as the CPU of the host is compatible with what they were compiled for.

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