The most dramatic disadventage of kvm guest is block device I/O, so I wouldn't recommend to virtualize file server if it is not necessary. In my case on host ntpd configured as source for virtual dc, and bind9 configured as type=slave for zones hosted on dc, (make shure that srv records in _msdcs.mysambadomain.local are resolving when virtual dc is down) and smbd fileserver with "winbind offline logon = true" in smb.conf. it works on HP Microserver G7 with AMD Turion II CPU and 2GB RAM and serves 15 clients in small office + it's also hosts asteriskPBX guest... All issues that I mentioned are true when there is only one dc in network and it runs as kvm guest. If it's not your case and you have other dc online when fileserver starts. Consider your virtual DC as phisical machine and everything will be fine... On 26.12.2016 21:06, Miguel Medalha wrote:> > >> i have a fiew production sites, where samba file servers running > their dc >> as kvm guests. No problems so far. > > >> Pay attention for dc time sync on startup. > > >> Shutdown (not suspend) guest on host shutdown. > > >> Make shure that appropriate dns server is available for host and > guest >> dc on startup. > > Thank you for your input. I am grateful that you warned me about the > issue of DNS. Of course now the AD DC will boot AFTER the file server. > I hadn't thought about that aspect and I am sure I would meet it later > in a more unpleasant way :-) > > Of course I could also virtualize the file server. My doubts are > related to the fact that it has a lot of physical disks containing > several Terabytes of data and this is a production machine that I > don't have much time to play around with. Would those disks be > available to a virtual machine as they are now, without first > converting them to virtual disks? >-- C уважением, Петров Андрей ---------------------- Email: petrov at solid-it.ru tel: +79261813797
Is kvm I/O realy disadventage? I use samba file server as kvm guest (LVM storage pool) in some setups and disn't notice any problems. Sequential read/write speed isn't noticeably different from non-virtualized samba host. Did I miss something and should expect sudden trouble? In a letter dated Tuesday, December 27, 2016 2:12:59 MSK by Andrei Petrov via samba wrote:> The most dramatic disadventage of kvm guest is block device I/O, so I > wouldn't recommend to virtualize file server if it is not necessary. > In my case on host ntpd configured as source for virtual dc, and bind9 > configured as type=slave for zones hosted on dc, (make shure that srv > records in _msdcs.mysambadomain.local are resolving when virtual dc is > down) and smbd fileserver with "winbind offline logon = true" in smb.conf. > it works on HP Microserver G7 with AMD Turion II CPU and 2GB RAM and > serves 15 clients in small office + it's also hosts asteriskPBX guest... > All issues that I mentioned are true when there is only one dc in > network and it runs as kvm guest. > If it's not your case and you have other dc online when fileserver > starts. Consider your virtual DC as phisical machine and everything will > be fine... > > > On 26.12.2016 21:06, Miguel Medalha wrote: > > > > >> i have a fiew production sites, where samba file servers running > > their dc >> as kvm guests. No problems so far. > > > > >> Pay attention for dc time sync on startup. > > > > >> Shutdown (not suspend) guest on host shutdown. > > > > >> Make shure that appropriate dns server is available for host and > > guest >> dc on startup. > > > > Thank you for your input. I am grateful that you warned me about the > > issue of DNS. Of course now the AD DC will boot AFTER the file server. > > I hadn't thought about that aspect and I am sure I would meet it later > > in a more unpleasant way :-) > > > > Of course I could also virtualize the file server. My doubts are > > related to the fact that it has a lot of physical disks containing > > several Terabytes of data and this is a production machine that I > > don't have much time to play around with. Would those disks be > > available to a virtual machine as they are now, without first > > converting them to virtual disks? > > > > >
On Thu, 29 Dec 2016, Filippe LeMarchand via samba wrote:> Is kvm I/O realy disadventage? I use samba file server as kvm guest (LVM > storage pool) in some setups and disn't notice any problems. Sequential > read/write speed isn't noticeably different from non-virtualized samba > host. Did I miss something and should expect sudden trouble?It depends greatly on your setup. Paravirtualized I/O (/dev/vdX) and raw volumes (or LVs) will give you nearly native performance. As long as you are using paravirtualized I/O you will probably not notice the difference unless your server is very heavily loaded. Also, unless you have a lot of spindles or are using fast SSDs, your disk I/O is more likely to be the weak point anyway.
Am 29.12.2016 um 17:01 schrieb Filippe LeMarchand via samba:> Is kvm I/O realy disadventage? I use samba file server as kvm guest (LVM > storage pool) in some setups and disn't notice any problems. Sequential > read/write speed isn't noticeably different from non-virtualized samba > host. Did I miss something and should expect sudden trouble?no with paravirtualized IO there is no real-world difference between a virtual machine and bare-metal and in reality since you need only *two* horse power hosts instead a dozen machines you can concentrate your money in fast disk-spindles on both hosts - at the end you will get for the same amount of money more performance for everything * one really fast CPU in both hosts * a lot fo RAM in both hosts * a realy fast disk spindle in both hosts the rest is the job uf the scheduler and it will outperform 10 low-range machines with middle to slow disks at this point of time you need really good reasons for not isntall a hypervsior on your baremetal as first step
29.12.2016 19:01, Filippe LeMarchand пишет:> Is kvm I/O realy disadventage? I use samba file server as kvm guest > (LVM storage pool) in some setups and disn't notice any problems. > Sequential read/write speed isn't noticeably different from > non-virtualized samba host. Did I miss something and should expect > sudden trouble?No you shouldn't. What I meant is: of allinsignificant disadvantage aspects of virtualization I/O is the most significant. In Miguel's case i just see no reason to move fileserver to guest if it's already up and running in production. In scenario i described earlier at first implementation I made 3 guests: dc, fileserver and asterisk. I had problems sharing 2GB of RAM for all of them. ksm gives some relief, but it eats CPU time and Turion II Neo N40L has not much of it. moving fileserever to host gave me resources to launch windows guest so i can manage dsa.msc gpmc.msc and etc. without freezing host. At first sight it may seem better to put a new service in virtual environment, but in the end of the day you just got another host to maintain (update, fsck, monitor and all this stuff) -- C уважением, Петров Андрей ---------------------- Email: petrov at solid-it.ru tel: +79261813797