From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: a few may be wiki question Date: Tue, 14 Aug 2007 15:50:16 +0300 Message-ID: <46C1A508.9030809@qumranet.com> References: <46C19F33.40102@bppiac.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Farkas Levente Return-path: In-Reply-To: <46C19F33.40102-lWVWdrzSO4GHXe+LvDLADg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Farkas Levente wrote: > hi, > i try to setup a centos host server with kvm and a few guest os for the > first time. imho there is only a very limited docs about kvm (even if i > try to read them:-). so there are a few general questions: > - which is the recommended host config?: > - should i used x86_64 or i386 host kernel? i don't know in advance, > but probably most guest os will be 32 bit. is there any advantage or > disadvantage to use x86_64 as a host os? > If you have more than 1GB of RAM, 64-bit will be slightly faster. Otherwise there is no preference. > - i'll use kernel-2.6.18-8.1.8.el5, but i read in the announcement > for kvm-34: > "running on a host earlier than Linux 2.6.23-rc2 will experience > a slight performance degradation" > what does exactly means and how much is the "slight"? or if i use > older kernel it's better to use kvm-33? > It's likely not measurable for most uses. It's recommended to always use the latest kvm version in order to get the latest fixes and enhancements. > - i read in faq 3.6: > "for the host. 1GB is probably a minimum configuration for the host > OS." > does this means i have to reserve 1GB for the host os? > No. That is the total amount of RAM on the host (and it's a recommendation -- you can work with less if you like). > it's strange for me just because eg with xen dom0 we use 256MB and > it was enough since dom0 don't have any real load. it's not the case > with kvm? > It depends on what the host is doing. If it isn't running any workload, even 128MB should be enough. > who much ram should i use for the guest os? > That's for you to choose; select as much memory as the guest needs and you can give it. > eg if i use 6 guest then i need at least 6GB of ram? > If each guest gets 1GB, yes. But you can give guests less memory. > - is dynamic use of RAM for host operating system supported? > What's that? > - what is the recommended size for the host disk partition? > Whatever is sufficient for your distro. I use 10GB usually (FC6/F7). > - what is the recommended swap partition size for the host os ? > The regular recommendation of your distro. Size of RAM is usually ok. > - which is the recommended guest config? > - what is the recommended memory for a guest os? same as i would run > natively? > Yes. Depending on workload and budget. > - what is the recommended guest disk image format? should i use an lvm > partition as guest os partition (like in xen)? what is the > recommended format assuming that may be later i'd like to add new > guests and what is the performance differences (ie. which is the > fastest format)? > Depends on workload. lvm is fastest, qcow2 is most flexible and managable. If your guest is not issuing significant disk I/O, I'd recommend qcow2. Otherwise lvm. > - what is the recommended swap partition format and size for the > guest os ? > Whatever is recommended by the guest OS vendor. > - what is the current general state of kvm ie. stability, performance > support etc? i mean for non mission critical production server it's > worth to choose in stead of xen or not? > I find it very stable. Try it out! > i know most of my questions are too general, but almost all answer will > start as "it's depend on.." but still a general guideline would be useful. > > last but not least may be a kvm-user list would be useful where such > questions can send and not disturbing all the developers. > Well, my stance on this is that if a user needs to send such an email, then the application or documentation is missing and should be fixed. The developers need to be bothered until the situation is corrected. Having a users list is just a cover up for bad usability and documentation. I regard this type of email as valuable feedback, not disturbance. [now back to not writing documentation] -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/