Hi all, I''m just starting with XEN and I''ve few basic questions. My last goal is build a system with dom0 CentOS-based and domU CentOS-based too. So... 1) ¿Is LVM filesystem managment recommended? The CentOS partitioner uses LVM by default, but I can disable it manually. ¿Offers LVM any advantatge over tradictional partition system? 2) Same question about SELinux. -- Thanks, Jordi Espasa Clofent _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, May 03, 2007 at 01:16:07PM +0200, Jordi Espasa Clofent wrote:> Hi all, > > I''m just starting with XEN and I''ve few basic questions. > My last goal is build a system with dom0 CentOS-based and domU > CentOS-based too. > > So... > > 1) ¿Is LVM filesystem managment recommended? The CentOS partitioner uses > LVM by default, but I can disable it manually. ¿Offers LVM any > advantatge over tradictional partition system?You definitely want LVM in dom0. Makes setting up filesystems for domUs easy and convenient, with barely any overhead.> 2) Same question about SELinux.There is probably no point in having selinux in dom0, you should only ever let root in there. Marcin -- Marcin Owsiany <marcin@owsiany.pl> http://marcin.owsiany.pl/ GnuPG: 1024D/60F41216 FE67 DA2D 0ACA FC5E 3F75 D6F6 3A0D 8AA0 60F4 1216 "Every program in development at MIT expands until it can read mail." -- Unknown _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, May 03, 2007 at 06:34:13PM +0200, Jordi Espasa Clofent wrote:> En/na Marcin Owsiany ha escrit: > >On Thu, May 03, 2007 at 04:13:01PM +0200, Jordi Espasa Clofent wrote: > >>>You definitely want LVM in dom0. Makes setting up filesystems for domUs > >>>easy and convenient, with barely any overhead. > >>Ok. Indeed I think in create a dedicate LV for /var/lib/xen/images dir. > > > >Don''t! Just allocate as much space as you need for dom0 itself from the > >VG and then create a separate LV for each domU filesystem as needed. LVM > >is recommended over loop file images. > > Marcin, > > First of all, I''m sorry for this private message; I wanted to response > you into the public XEN mail-list but I mistook.Ccing xen-users, to give others a chance to comment.> Ok... let me understand your explanation... Currenty, I have this > partition scheme (according to df command): > > S. fitxers Blocs 1K Usats Lliures %Ús Muntat en > /dev/mapper/VolGroup00-LogVol00 > 75799584 18643672 53243416 26% / > /dev/hdb1 101086 30845 65022 33% /boot > tmpfs 478028 0 478028 0% /dev/shm > > So... ?what is the correct way you consider? ?Is this partition scheme > functional or I must consider another design in other clean-instalation > (whole SO)?The way I do it is create a /boot for GRUB, and a volume group taking up the rest of the disk. On the VG, create just two small LVs for dom0 - one for swap and another for root filesystem. Then you have the rest of the VG for domUs, etc. Marcin -- Marcin Owsiany <marcin@owsiany.pl> http://marcin.owsiany.pl/ GnuPG: 1024D/60F41216 FE67 DA2D 0ACA FC5E 3F75 D6F6 3A0D 8AA0 60F4 1216 "Every program in development at MIT expands until it can read mail." -- Unknown _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On May 03, 2007 09:50:36 Marcin Owsiany wrote:> The way I do it is create a /boot for GRUB, and a volume group taking up > the rest of the disk. On the VG, create just two small LVs for dom0 - > one for swap and another for root filesystem. Then you have the rest of > the VG for domUs, etc.Why do you put the / ("root") partition n the LVM? What if something happens to the LVM "volume group", and renders your system completely unbootable?? -Alan M. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> I''m just starting with XEN and I''ve few basic questions. > My last goal is build a system with dom0 CentOS-based and domU > CentOS-based too. > > So... > > 1) ¿Is LVM filesystem managment recommended? The CentOS partitioner uses > LVM by default, but I can disable it manually. ¿Offers LVM any > advantatge over tradictional partition system?LVM is more flexible - you can easily create a new logical volume for each guest''s virtual disk. You can distribute guest disks across multiple physical volumes, etc etc. Good stuff for management and it should perform well too. Running LVM in the guests isn''t really that useful, though and makes it harder to access guest filesystem contents from dom0. I''d suggest you just use LVM on the host. Using normal files as the backing storage for guests is good for playing around. Use tap:aio rather than file: mode to access this storage is preferred - tap tackles some unpleasant problems with the file: mode which uses the loop-device (nb. I''m talking about paravirt domains, things are a little different for HVM domains). LVM is probably the best storage solution for a production machine, unless you decide to use a SAN or something like that...> 2) Same question about SELinux.I think RHEL / CentOS 5 has an SELinux setup that''s designed to work OK with Xen. If you use file-backed images you have to put them in a specific directory or it''ll complain. I don''t know how SELinux would interact with LVM-based volumes, though. I''m not sure how useful SELinux is for a Xen dom0 because I''m not sure what RHEL / CentOS put in their default config. You could use it for confining other services, but you shouldn''t really be running services in dom0 anyhow... Running SELinux in guests has all the same benefits of running it on a native machine though, so you should definitely consider that if it fits your usecase. HTH, Cheers, Mark -- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Alan Murrell wrote:> On May 03, 2007 09:50:36 Marcin Owsiany wrote: > >> The way I do it is create a /boot for GRUB, and a volume group taking up >> the rest of the disk. On the VG, create just two small LVs for dom0 - >> one for swap and another for root filesystem. Then you have the rest of >> the VG for domUs, etc. >> > > Why do you put the / ("root") partition n the LVM? What if something happens > to the LVM "volume group", and renders your system completely unbootable?? >Because you can resize such partitions more dynamically, and because RedHat''s default instlallers readlly try to insist on doing this, and because by distributiong the LVM across multiple partitions you can noticeably improve performance. Doing it inside the Xen instance is not as useful, though. Let Dom0 do the LVM! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users