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Re: linux standard layout

From: Jan-Ivar Mellingen <jan-ivar(dot)mellingen(at)alreg(dot)no>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: linux standard layout
Date: 2010-03-09 20:18:35
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-admin
Tom Lane skrev:
>   But a virtualization layer can kill your performance and/or
> reliability.  Ask hard questions about why that decision is being
> imposed on you and what benefits it will have.

I have been following this discussion, and I feel I have to make a comment.
Our company has moved all servers to a fully virtualized environment 
Instead of having to deal with a bunch of physical servers we now have a 
clean setup with two 'irons' running vmware, and a pack of disks (SAN). 
If any of the disks should fail, we can simply exchange it without 
disturbing the running servers.
If one of the physical machines have some trouble it automatically 
switches to the other one, again without disturbing the running servers. 
If we wish, we can move a running PosgreSQL server from one physical 
machine to another without stopping it or disconnecting users.
- Want more RAM? Adjust the value on the virtual machine.
- Want another CPU? Just add one.
- If I need another PostgreSQL server I just ask for a clone and it is 
ready in 10 minutes. You can even clone a running server, data and all.
If I need the server for testing I can download a clone to my own 
computer and run it there under VMware Workstation or Player.
I can make a new virtual machine on my own PC and when I am done setting 
it up I give it to the IT guys and they start it on the big irons.
This setup is extremely flexible and saves A LOT of work. It also has a 
huge impact on the reliability and performance. The performance of the 
virtual servers are awesome.

BTW: we are running PostgreSQL 8.3 and 8.4 servers on Ubuntu linux on 
the virtual machines.

On my own development computer I am also running virtual machines; one 
running development tools, another a PostgreSQL server, a Windows 
machine running some client application using the database server etc.
I will prefer a virtualized environment over physical machines any time.
Regarding performance, on my development machine (a Lenovo ThinkPad 
W700) the virtual PC's are running at about 90-95% of the speed on the 
same hardware without virtualization.

Regarding 'pulling the plug' on the servers: Physical or virtual, always 
use a UPS. You can pull the plug as much as you like. When the power is 
about to run out it signals the server, which shuts down cleanly.
Our servers have dual powersupplies, connected to separate UPS'es on 
separate power sources...

In a nutshell, I am heartly recommending virtualization.
And - I do not want to start a discussion about it. Just sharing my opinion.


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Subject: Re: linux standard layout
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