Hi, i would like to know where would you guys install the unraid to as a dom0?

will it affect the performance of the domU if the unraid dom0 on usb?

Thanks

usb, the entire operating system is loaded onto memory at startup and usb is only used for reading licenskey and some lite configs

Thanks for your reply, how much ram does it need to assign to unraid dom0? can i have another usb to backup the dom0 and not losing the vm config?

there is nothing of dom0 to back up other than keeping a copy of your flash drive.  And even then generally the really important things to keep are your license key-file and your Superdat (which is the array config).  Everything else is easily recreated until you start getting fancy, and then you GO file is smart to have a copy of.

 

But of course it is even easier to share your flash over samba (via GUI), make a folder on your PC, and copy the entire flash over.  You can then unshared the flash if you want.  I do this literally every time I make a major change (upgrade, config change, new plug-in, etc).  It is very small. I label the folders [yyyy mm dd] [version] [special notes].  I have about 20 of them now.

 

The thing to understand is the flash loads a static image (bzroot, which never changes) into memory from which any changes are lost at reboot.  Then the flash is left completely alone with everything running from ram.  If there are system changes you need to make (like a cron job, or tweak specific to your system) that you want to survive a reboot then you do it via a scripts that runs at boot to change the fresh image that has been loaded into memory.

 

That might all sound like a pain, but it has the benfit of being very compact (fits on a small usb and loads quickly), lets you easily recover from a silly mistake because your host OS is a static image that loads into ram, and keeps flash writes to a bare minimum for longevity.

 

Now domU is another story.  The config is just a small file, but your vm.img and data.img files are of course usually gigs in size.  That will need to be stored somewhere NOT on the flash.  Many people use a cache drive, or an non-array mounted drive.  Putting a VM on the array would be slow because of the array write speed due to parity.  however keeping a copy of domU on the array is a great idea and lonix has written a nice little script that does it for you.  You just need to have that script copied into /etc/cron every boot via the GO script.

 

Now that I wrote that and can't be accused of being one of "those" forum people .... I will say there is a TON of info in the wiki to explain just genrally how unraid works.

 

http://lime-technology.com/wiki/index.php/UnRAID_Wiki

 

Because things are in flux the docs are lagging a bit, but there is utility in reading 4.7 and the incomplete 5.0 docs.  6.0 difference can be gleaned just from reading the change logs and the announcement threads.  Docs for that would be hard to write atm since it is in a pretty quick development cycle and so much stuff is being learned as we go re: Xen and VMs.

 

But [wink] what I just described above is unraid 101 stuff since very early versions.

 

Thanks for your reply, how much ram does it need to assign to unraid dom0? can i have another usb to backup the dom0 and not losing the vm config?

 

If you mean how much ram should you give unraid/dom0 via syslinux.cfg the answer is it depends, but unraid can run in as little as 512k.  1024 will be more than plenty for many people except when running one of the few memory hog plug-ins (cache-dir) a which point 4096 might be needed if you have a LOT of directories to cache in memory.  I'm running 1024 and that is probably overkill ever since I moved my plex media server out of com0 and into domU-archVM