Thanks... inline..
--- On Sat, 8/9/08, Anthony Liguori <[EMAIL PROTECTED]> wrote: > From: Anthony Liguori <[EMAIL PROTECTED]> > Subject: Re: KVM Management : Migration > To: [EMAIL PROTECTED] > Cc: "KVM List" <[email protected]> > Date: Saturday, August 9, 2008, 8:48 AM > jd wrote: > > Hi > > For migration to work, it is recommended to start > the VM with exact same params as the original VM. Can some > one clarify the minimum set that should be the same.. while > if others like VNC port Or default bridge can be different. > (as the target machine may have vnc port already used.) > > > > Anything that affects the hardware exposed to the guest > must be the > same. -vnc, -net tap, -monitor, etc. have no effect on the > hardware > exposed to the guest so they can be modified. > > > Also, if there are any compatibility checks for > migration that needed to be done for predicting successful > migration > > > > Note that a primary design goal of migration is that > failure will never > result in a lost VM so it is generally safe to try a > migration even if > there's a chance it may fail. > > > -- KVM version ? Same... similar.. any other way > to find if they are 'compatible' ? (As KVM is > released frequently) > > > > The format should be backwards compatible so version > checking isn't > necessary. > > > -- Processor same / similar ? Do we have a good > compatibility matrix somewhere ? I am assuming that there is > nothing specific to KVM but would like to confirm. > > > > We do our best to expose only a common subset of features > for guests. > Practically speaking, it's a trade-off. It is only > "safe" to migrate to > absolutely identical CPUs otherwise you risk the guest > miscalibrating > the TSC. > > In general, modern Linux guests can detect the TSC screwing > up and as > long as your going from a slower to faster system, it > should be okay (or > perhaps vice versa). Any ides about how this affects Windows guests ? > > > -- Memory availability : How to compute > availability of "enough" memory ? Free physical > memory ? Or some weight on available virtual memory/swap ? > weave in some knowledge of ballooning details. > > > > KVM supports memory overcommit so it simplifies and > complicates things. > A migration should always succeed regardless of memory on > the system but > performance may suffer because of swapping. So choosing > the best > migration target will have to take into account available > free memory, > how many VMs are on the system already (the potential > memory use for the > future), etc. > Interesting...so the migration would succeed even if the available memory is < required by VM. It will end up using swap space and performance would suffer. Thanks /Jd > Regards, > > Anthony Liguori > > > Any other checks ? > > > > Thanks > > /Jd > > > > > > > > -- > > To unsubscribe from this list: send the line > "unsubscribe kvm" in > > the body of a message to [EMAIL PROTECTED] > > More majordomo info at > http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
