(r8) ChrisCookeSandbox < Sandbox

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---+++ Which server for a new KVM guest?

To find out, answer these questions then look at the table below:
   * Does the guest have to be at a particular site, or on a particular subnet?
   * Does the guest have to be fast? The fastest machine is [[MPUjubileeDetails][jubilee]].
   * Does it need to be very reliable? If so choose a "fully supported" server; choose SAN storage (so the VM can be resurrected if the server dies); and use a server which supports migration (so the VM can keep running through planned server downtime).
   * Is it a temporary or test machine? If so use [[MPUcircleDetails][circle]], or use local disk storage rather than SAN (see the individual server pages for details).
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   * Is there room in your chosen storage pool (see individual host pages for storage pool details)? To find out, login to the server, ==nsu==, then ==pvdisplay== to find the amount of free space in each pool.
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|  *Host<br><sub>click host for details</sub>*  |  *Performance*  |  *Storage<br>Locations<br><sub>see below</sub>*  |  *Site /<br>Subnets*  |  *Hot Migration<br><sub>see below</sub>*  | *Comments*  |
| [[MPUjubileeDetails][jubilee]] |  Fastest  |  SAN,<br> local disk  |  IF  |  Not yet  | Fully supported. |                |
| [[MPUbakerlooDetails][bakerloo]] |  Slowest  |  Elderly disk array  |  IF  |  Not yet  | Essentially a backup for [[MPUjubileeDetails][jubilee]]. |
| [[MPUpiccadillyDetails][piccadilly]]  |  Medium  |  SAN,<br> local disk  |  KB  |  Yes, to/from [[MPUnorthernDetails][northern]]  | Fully supported. | 
| [[MPUnorthernDetails][northern]] |  Medium  |  SAN,<br> local disk  |  KB  |  Yes, to/from [[MPUpiccadillyDetails][piccadilly]]  | Essentially a backup for [[MPUpiccadillyDetails][piccadilly]]. |
| [[MPUcircleDetails][circle]] |  Medium  |  Local disk only  |  AT  |  None  | Use at your own risk. [[MPUcircleDetails][Circle]] is a "hot spare" so may have to be redeployed at short notice. If this happens then _VMs may have to be deleted_. Good for temporary or test VMs. |
<!--| _Click host for details_ |                  |                                    |       |  [[#Notes_On_Migration][<em>Notes on migration</em>]]  | |-->

---+++++ Notes on Storage Locations
   1. A guest's disk space is created in one of the host's _storage pools_.
   1. Some storage pools are on SAN space and some are on the host's local disk space.
   1. SAN will normally be a little faster than local disk.
   1. If the host suffers sudden hardware failure, SAN storage can be mounted on another host. Local disk storage can't.
   1. However, local disk isn't used by multiple servers, so it may have more _predictable_ performance.

---+++++ Notes On Migration
   1. Hot migration seems to work well but for us it's _experimental_ as yet (June 2012). 
   1. A migrating host will have a perceived downtime of 2 or 3 seconds.
   1. The MPU will do the migration for you, please don't do it yourself.
   1. We're working on cold migration.

Topic revision: r8 - 19 Jun 2012 - 11:08:29 - ChrisCooke

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