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MiamiBeachCop

Why Virtual Hosts

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Why are some hosting companies using virtual hosts? What advantages does this give, either from a performance or security perspective. Why not a virtual host for each user, and just some users on a virtual host?

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This should not have been moved, it directly relates to networking and security.

 

@segger

 

What security advantages would there be as opposed to jails?

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This should not have been moved, it directly relates to networking and security.

 

@segger

 

What security advantages would there be as opposed to jails?

But it isn't about networking and security, you are talking about the technical benefits of a, well, technology.

You could also put this in Windows for Windows VM's, or Apple for Parallels, or F&OSS for Xen.

 

 

See what I am getting at.

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Actually, I am only asking about the security benefits or reasoning behind using virtual machines for shared hosting, which also directly relates to the application layer of networking. So.., networking and security would seem to fit..

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Because I don't have enough information. From what I do know I see no reason to use virtual machines for shared hosting.

 

I am not writing an assignment, I just recently saw a shared host where a webserver was on a virtual machine, and could not figure out any advantage or reason for this, except bad administration.

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Because I don't have enough information. From what I do know I see no reason to use virtual machines for shared hosting.

 

I am not writing an assignment, I just recently saw a shared host where a webserver was on a virtual machine, and could not figure out any advantage or reason for this, except bad administration.

Fucking ouch.

I'm a sysadmin and I pretty much dream about VM's.

 

 

Why?

They save rack space and resources thereby increasing efficiency.

They can be made redundant/HA, allow clustering, auto failover, quick provisioning, easy management.

You can also run WinXP/Vista/2K/2K3, Debian, CentOS, OpenSolaris and Redhat all on the one VM server rather than having a dedicated box for each (which goes back to my first point).

 

 

To run them successfully you need to be a good sysadmin, so maybe the ones you saw were just shit.

I don't understand why you think it was bad administration.

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There is more convenience for you, the administrator, at the sake of performance.

 

There is little point on using virtual machines for shared hosting, when there is no security or performance advantage. They could have accomplished the same thing using a jail with far less overhead. If you dream about VM's why are you not using them?

 

The other problems are magnified physical failures. If one physical server goes down how many VM's is that? There a quite a few other issues with VM'S, basically using them when not necessary and will degrade performance is bad administration.

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The other problems are magnified physical failures. If one physical server goes down how many VM's is that? There a quite a few other issues with VM'S, basically using them when not necessary and will degrade performance is bad administration.

That failure magnification is as much a fault with shared hosting and jails - with the added penalty that you can't transparently shift the load to another VM server.

 

Performance has many faces. Straight and simple CPU speed is usually the least important in a hosting centre. Uptime, Flexibility for upgrades and Power efficiency are probably more important.

 

There's nothing to stop a host using shared hosting (jails etc) inside VMs. It would give you failover and migration options at a course level, but not allow you you seamlessly migrate individual customers.

 

It's not bad administration if it makes the job easier. Good administration is where problems are planned for and the contingency plans on failure etc flow automatically and with minimum effort.

There's nothing ideal about some sys admin being called in at 2am to urgently fix system failures because downtime is costing the host megabucks due to failed SLAs.

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+1 to the above.

 

We do use VM's at work. We have two main (beefy) physical servers running one instance of each VM in active/passive failover.

There is no loss of performance, we save about 6 rack spaces, we increase efficiency and we increase our uptime and flexibility.

 

 

I reckon you should read up on virtualisation a little more, some of the techniques used are pretty much on par with bare metal machines.

 

Basically as stadl said, there is more to it than just security and performance. (But you aren't a sysadmin are you?)

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The correct answer is... I can provision a new server, with whatever operating system, in a few clicks, rather than popping down to the shop, spending a wad of cash, and having to then rack up a new server.

 

EDIT: Also when some bellend rents a "server" to do whatever they like on, it's VERY easy to restore (generic image for generic hardware) WHEN they break it.

Edited by brains

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Not to mention that it's much easier to move a guest VM from one host to another in the event of hardware failure (especially with SAN and other pooled storage technologies) than to re-instate a bunch of Apache (or whatever) virtual hosts, and all the related IP arsehattery.

 

VM solutions like VirtualIron, VMware ESX and Citrix XenServer can migrate VMs between hosts with next to no downtime.

Edited by SquallStrife

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The correct answer is...

 

Nah, you're just a bad admin!

 

Yep, you can tell when he said "click" instead of "typed" :P

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The correct answer is...

 

Nah, you're just a bad admin!

 

Yep, you can tell when he said "click" instead of "typed" :P

 

Oooh burn!

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