# Moving from VPS to dedicated box. Thoughts re Xen? **URL:** \ **Category:** Deployment\ **Created:** [January 30, 2007, 6:35pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903 "2007-01-30T18:35:25Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 30, 2007, 6:35pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/1 "2007-01-30T18:35:25Z")
I’m going to be moving from a VPS to a dedicated box in the next few weeks and am thinking about configuring it with Xen, and wondered if anyone had any thoughts about this and specifically how the various instances should be set up. Bit of background – I’m not a computer professional by background. Got into it through sorting the IT for a small company I ran and ending up building our website (PHP hackery) and setting up a couple of Linux boxes. Rails (and Ruby) have been a revelation, and added some sorely needed structure to my coding. All this means I’m learning as I go along, and sometimes it’s a steep learning curve (for example, I’ve had zero experience of Xen). Currently I’m on a VPS with 160MB of Ram, running Debian 3.1, nginx and mongrel-cluster, all of which is fine (well, Debian’s a bit of a pain sometimes, what with having to building half the things you need from source because the sources are too old, but it’s a pain I’m sort of familiar with). So, questions: 1. Xen – a good idea at this stage? 2. Debian – the right distro for Xen, or would Ubuntu server be better? 3. How should I divide the instances – I’m thinking, for the moment, of nginx + mongrel instances on one instance, MySQL on another, and possibly asset storage (photos, cached files) on a third. 4. I’m using the db for sessions at the moment and only using fragment caching, on the FS. Should I rethink these and look at memcached (something else I know nothing about) 5. What about memory allocation between the instances (and would 2GB be a reasonable amount of total memory to start with) 6. Any gotchas? Hope I’m not taking the piss with all these questions. Any suggestions gratefully received, Chris ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 1:37am UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/2 "2007-01-31T01:37:15Z")
On Jan 30, 9:57 pm, “ChrisT” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 1. Debian – the right distro for Xen, or would Ubuntu server be Debian decided to go with OpenVZ [[http://openvz.org/](http://openvz.org/) ], so the packages are in etch by default. Ubuntu decided to go with Xen, so you can find all needed packages in edgy. If it is just for security separation, take a look on OpenVZ - not a bad option at all 😉 Memcached? Will you REALLY have a LOT of instances? Because memcached make a sence just in this case - shared storage. My opinion: go with AR session store and if not fast enough - sql sessions store [ http:// [railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-](http://railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-) store ] Gotchas? nginx is good with serving static files (assets), why to not put them together (nginx+assets) and have mongrels in another container ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 2:41am UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/3 "2007-01-31T02:41:18Z")
On 1/30/07, ChrisT [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I’m going to be moving from a VPS to a dedicated box in the next few > weeks and am thinking about configuring it with Xen, and wondered if > anyone had any thoughts about this and specifically how the various > instances should be set up. Congrats. I think this is a really forward looking solution. If you deploy on a single box in this fashion, when the traffic comes you’ll have an entirely clear path to expanding: 1. Order new box 2. Install Xen 3. Determine which process is causing pain 4. Move already entirely configured environment onto new box 5. Revel in the new speed 6. Realize you could have done 4 _while the instance was running_, if you had SAN storage! > All this means I’m learning > as I go along, and sometimes it’s a steep learning curve (for example, > I’ve had zero experience of Xen). The extra overhead of learning a few critical Xen commands to manage the system is trivial compared to the advantages, IMHO. > So, questions: > > 1. Xen – a good idea at this stage? 🙂 > 1. Debian – the right distro for Xen, or would Ubuntu server be > better? I’d recommend Gentoo, but that’s just me. > 1. How should I divide the instances – I’m thinking, for the moment, > of nginx + mongrel instances on one instance, MySQL on another, and > possibly asset storage (photos, cached files) on a third. I’d split them this way: 1. nginx with the shared storage mounted, proxying to: 2. at least two separate instances running mongrel\_cluster, each accessing 3. NFS storage for this instance and 4. MySQL on its own instance and 5. a MySQL replica because you’ll be happy to have it when you need it, and it makes backing up the DB while the system is live very easy. > 1. I’m using the db for sessions at the moment and only using fragment > caching, on the FS. Should I rethink these and look at memcached > (something else I know nothing about) I wouldn’t worry about it until you need it. When you do, bring up new Xen instances for memcache. > 1. What about memory allocation between the instances (and would 2GB > be a reasonable amount of total memory to start with) 1. nginx @ 128M-192M 2. mongrel\_cluster instances @ 256M-384M (determined by actual usage) 3. I’m really not sure what an NFS server needs, probably 128M-256M 4. MySQL @ 512M-1024M (I’d basically give it whatever you don’t use elsewhere) 5. MySQL replicas require very little RAM > 1. Any gotchas? Always. 🙂 – – Tom M. ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 9:08am UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/4 "2007-01-31T09:08:39Z")
stoyan wrote: > bad option at all 😉 > > > Stoyan Thanks for this. V. useful. Cheers Chris ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 9:06am UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/5 "2007-01-31T09:06:39Z")
Tom M. wrote: > > So, questions: > > I’d recommend Gentoo, but that’s just me. > > 1. at least two separate instances running mongrel\_cluster, each accessing > > 2. I’m really not sure what an NFS server needs, probably 128M-256M > > 3. MySQL @ 512M-1024M (I’d basically give it whatever you don’t use elsewhere) > > 4. MySQL replicas require very little RAM > > > 1. Any gotchas? > > Always. 🙂 Tom Many thanks for all this great info. Much appreciated. Cheers Chris ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 3:24pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/6 "2007-01-31T15:24:24Z")
Stoyan, > Memcached? Will you REALLY have a LOT of instances? Because memcached > make a sence just in this case - shared storage. My opinion: go with > AR session store and if not fast enough - sql sessions store [ http:// > [railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-](http://railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-) > store ] SQL Session Store is easy to setup and faster than AR, there is no reason to try first with AR for sessions. This list rocks. – Aníbal Rojas > **[RUBYCORNER.COM](https://www.rubycorner.com/)** > > RUBYCORNER.COM - Contact us for any business inquiries > **[Home - Has Many Developers](https://hasmanydevelopers.com/)** > > We are the best choice for your building design and development ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [February 1, 2007, 2:56pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/7 "2007-02-01T14:56:25Z")
Tom, > Down that road lies the (personally experienced!) insanity of > pre-optimization of everything, because it’s _all_ easy. > > Only…it’s not. 🙂 And even if it was (or is!) it takes time and > must be maintained. > > I think sql-session-store is super-cool, and I cannot express my > thanks to Stephan Kaes adequately, but most people simply don’t need > it (immediately). I completely agree with you, but (in my experience) the setup and maintenance of AR Sessions Store and SQL Session Store are just the same. So why don’t use the fastest one? And yes Stephan must receive some kind of recognition from the community for his bright work 🙂 – Aníbal Rojas > **[RUBYCORNER.COM](https://www.rubycorner.com/)** > > RUBYCORNER.COM - Contact us for any business inquiries > **[Home - Has Many Developers](https://hasmanydevelopers.com/)** > > We are the best choice for your building design and development ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [January 31, 2007, 8:27pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/8 "2007-01-31T20:27:59Z")
On 1/31/07, Aníbal [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > Memcached? Will you REALLY have a LOT of instances? Because memcached > > make a sence just in this case - shared storage. My opinion: go with > > AR session store and if not fast enough - sql sessions store [ http:// > > [railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-](http://railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-) > > store ] > > SQL Session Store is easy to setup and faster than AR, there is no > reason to try first with AR for sessions. Down that road lies the (personally experienced!) insanity of pre-optimization of everything, because it’s _all_ easy. Only…it’s not. 🙂 And even if it was (or is!) it takes time and must be maintained. I think sql-session-store is super-cool, and I cannot express my thanks to Stephan Kaes adequately, but most people simply don’t need it (immediately). – – Tom M. – CTO, Engine Y. ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [September 25, 2007, 11:05pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/9 "2007-09-25T23:05:39Z")
That is my opinion of Xen 🙂 It’s great as a way to segment applications for security purposes in say a shared hosting environment, it’s also sweet in a staging/development environment for quickly building new machines. But in a dedicated, static deployment environment, I don’t see the value (and I don’t see the scalability either) besides possibly being able to easily move to another environment (but how often does that really happen in a deployed application?) In your example of splitting mysql into a virtual machine and Rails/mongrel in a virtual machine as opposed to running them both on a dedicated operating system, you are now running a two full operating systems instead of two processes (or groups of processes). I am sure there are many on this list that disagree 🙂 ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [September 25, 2007, 11:02pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/10 "2007-09-25T23:02:31Z")
I guess the idea would be to make things scale better – so it’s easier to move to a multi-server setup if and when. However, I could be just getting seduced by the buzz around Xen – hence the post. ---
**Author:** ![christ](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/8e8cbc/32.png) [@christ](https://www.ruby-forum.com/u/christ)\ **Post date:** [September 25, 2007, 11:07pm UTC](https://www.ruby-forum.com/t/moving-from-vps-to-dedicated-box-thoughts-re-xen/83903/11 "2007-09-25T23:07:44Z")
I guess I have to ask, what are your goals with moving to a Xen setup?