Whats the difference between vps and dedicated server, both managed?

[Slavik]

OpenVZ is different ... I have specifically said that, so we're not talking about OpenVZ here and that's why they are cheap ... because they squeeze the hell out of the server ... nothing stopping them

if you have 8 cores and someone else is reporting the same thing then he must have the same share as you or you guys aren't using XEN.

I think xen was the one I looked at a while back, if I remember correctly the layer of virtualisation actually enforces limits on the proccess io list, so if you have 4ghz of cpu power split between 4 users, it would stack the proccesses simply put 1,2,3,4,1,2,3,4,1,2,3,4 or if you have it split unevenly beween 3 users with 2ghz to one user and 1ghz to two users it would stack it 1,1,2,3,1,1,2,3,1,1,2,3

It was quite complicated, but thats the jist i got of it.

 

[Floris]

In my opinion a VPS is the starter solution for those who take their site seriously and want to get shell access, super user access, and more resources and space available to them for only a few bucks more a month. Managed or not.

And a dedicated box can be managed as well, or not .. and are great for bigger web sites who need their own whole server, so its not getting slowed down by other elements, such as other virtualization accounts.

 

[Shamil]

In my opinion a VPS is the starter solution for those who take their site seriously and want to get shell access, super user access, and more resources and space available to them for only a few bucks more a month. Managed or not.

And a dedicated box can be managed as well, or not .. and are great for bigger web sites who need their own whole server, so its not getting slowed down by other elements, such as other virtualization accounts.

Very well said - though, I've got my websites on an array of VPS, for example, I've got Database/Web on one VPS, whilst mail server on another VPS (Mail server isn't used that heavily, but it is an Exchange 2010 server).

 

[Jason]

OpenVZ is different ... I have specifically said that, so we're not talking about OpenVZ here and that's why they are cheap ... because they squeeze the hell out of the server ... nothing stopping them

if you have 8 cores and someone else is reporting the same thing then he must have the same share as you or you guys aren't using XEN.

This simply isn't true. OpenVZ, ESXi, Xen, etc. can be configured in a number of different ways. You can have "dedicated" CPU cores, absolute shares of CPU where any slack CPU-time is shared on a best effort basis, or apply a proportionally weighted scheduling priority for sharing CPU based on a domain's sharing weight. The latter is the more common practice. Regardless, with a VPS setup, you are sharing resources with other users in some way, shape or form. Sure, there may be guarantees/limits, but the machine(s) is/are not solely dedicated to your domain.

 

[Blandt]

This simply isn't true. OpenVZ, ESXi, Xen, etc. can be configured in a number of different ways. You can have "dedicated" CPU cores, absolute shares of CPU where any slack CPU-time is shared on a best effort basis, or apply a proportionally weighted scheduling priority for sharing CPU based on a domain's sharing weight. The latter is the more common practice. Regardless, with a VPS setup, you are sharing resources with other users in some way, shape or form. Sure, there may be guarantees/limits, but the machine(s) is/are not solely dedicated to your domain.

Yes OpenVZ manages memory differently than all the others. When memory is available from other instances and you need it then OpenVZ has no problem assigning it to you : now that's sharing ..

The others do not share. Resources are divided and that's a big difference. to say that my neighbor instance will drag mine because its stretching it's resource and that it will affect me in anyway in a XEN environment that's simply not true.

My point is : sharing and dividing resources aren't the same thing and I am not sharing in any way shape or form !

CPU scheduling is another science all on its own. 16 cores divided into 16 VPSs, each VPS will give you the same performance as a comparable 1 core dedicated server.
Dean has mentioned something very important : your provider .. it works the same way : buying a dedicated server or a VPS

going to the cloud has the same principles, instead of dividing resources, we multiply them

 

[Jason]

Yes OpenVZ manages memory differently than all the others. When memory is available from other instances and you need it then OpenVZ has no problem assigning it to you : now that's sharing ..

The others do not share. Resources are divided and that's a big difference. to say that my neighbor instance will drag mine because its stretching it's resource and that it will affect me in anyway in a XEN environment that's simply not true.

My point is : sharing and dividing resources aren't the same thing and I am not sharing in any way shape or form !

CPU scheduling is another science all on its own. 16 cores divided into 16 VPSs, each VPS will give you the same performance as a comparable 1 core dedicated server.
Dean has mentioned something very important : your provider .. it works the same way : buying a dedicated server or a VPS

going to the cloud has the same principles, instead of dividing resources, we multiply them

Again, you're talking about specific configurations as if they apply across the board. I've setup my fair share to know this isn't the case. It is possible to share resources within a Xen setup. CPU is one of those resources, even if you have an allocated guarantee. Unless you have a dedicated cpu/cpu core, you're sharing (i.e., virtual CPUs that take turns running on the physical CPUs) -- the latter is the most common practice amongst providers. It has nothing to do with whether your usage affects other accounts or not. The scheduler ensures fair allocation, and that the CPU wastes as few cycles as possible.

For instance, cycles that are spent servicing I/O by domain 0 are not charged to the actual responsible domain, which can lead to situations where I/O intensive clients get a disproportionate share of CPU usage.

I will admit Xen does a good job at providing a good level of isolation, which is why its my first choice when turning to virtualization. In paravirtualized mode, it doesn't expose hardware drivers to domUs, which eliminates one huge attack vector. It also does a fairly good job at securing shared resources, though the emphasis is on enforcing performance isolation rather than preventing attacks on the domU from other domUs (which theoretically is possible).

It boils down to semantics. Yes, resources are allocated (divided), but that's still technically sharing. The machine is not dedicated to your sole use. And, depending on configuration, it's entirely possible for other users to have a detrimental affect on your usage of the server, regardless of whether you are using Xen, ESXi, etc -- which is probably one of the biggest reasons security-oriented people go the dedicated route.

The cloud isn't all that different, either. It's a vast pool of shared resources.

Anyway, I don't have anything against virtualization / cloud computing. We run a few different apps within the cloud, and stand alone VPS' for development and database replication (backups). Regardless, though, it's still shared resources.