Table of Contents
Advantages and disadvantages of virtualization and LXC
LXC sounds great, running multiple separated linuxes is a great thing (from a security point of view, and ease of maintenance If you someday discover your mailserver-vm is not working You might run into all kinds of problems AND LIMITATIONS. Yes: limitations, because there are some things that won't run correctly on lxc (yet).
Advantages:
- Easier maintenance and backup of individual virtual machines than one 'big' linux server
- Running different 'servers' on one physical computer saves hardware and power costs
- Security separation, hardware access from inside a vm may be restricted.
Disadvantages:
- Speed issues if too many vm's are using the same hardware at the same time (especially hard drive access, recommend a SSD).
- If hardware breaks, all virtual machines machines are affected.
- More machines to administrate/monitor/update (now you've got to update/patch/secure more 'computers' than if everything would have been installed on a single server).
- Might have problems accessing hardware, as access to that hardware might be restricted (?)
- By design, can't install NFS server (in kernel mode) in a container.
- Can't use pcap/trafshow/ettercap/.. traffic display utilities (?) (experienced myself, but yet to confirm).
- All logs are shared (?) (still have to test out how much this is true, and how it can be changed).
Alternatives to lxc
Wikipedia: Comparison of (platform) virtual machines (lxc, KVM, OpenVZ, and many more)
If I find lxc to be unfit/unsuitable for my purpose, I will have a look at KVM (Kernel-based Virtual Machine), though it will require other hardware.. Another site that lists a few of them is the Debian system virtualization portal. /*
unsorted links
- The answer is yes, you can install it (QEMU) even on Machines without KVM installed for creating the image/testing/installing guest-system(s)/ whatever reasons.
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Decisions on hard & software
Even before starting installing the lxc software, there are some important(?) decisions to make:
- Buy a SSD to lower hdd access time to speed things up [link] (12-12-2010: Just bought me a OCX Vertex 2 60GB review 1 2!)
- what filesystem to use, for snapshotting & data deduplication [link], hard links? Wikipedia: Comparison of file systems
- Buying a computer with a cpu supporting virtualization (Intel VT-x, VT-d, and the AMD counterparts […]) (LXC can however do fine without the virtualization technologies found in newer cpu's)
/* will lxc use these technologies or is it just for KVM?
todo: links to other sites, full- vs. para-virtualization; kvm vs lxc vs xen vs vmware vs virtualbox */