On Wed, Mar 07, 2007 at 02:20:11PM -0800, Hanks, Dan wrote: > > On Wed, Mar 07, 2007 at 01:50:43PM -0800, Hanks, Dan wrote: > > > I've been able to kickstart a number of VMs using the virt-install > tool, > > > and so far have had pretty good success. One aspect of these > installs > > > has me a bit concerned, though. In most cases, anytime the kickstart > > > needs to do intensive disk activity (such as formatting partitions, > or > > > installing all the rpms) there are noticible hangs, which I'm > guessing > > > come from some kind of IO wait. The result is that a kickstart which > > > should take < 10 minutes ends up taking a half-hour or so. > > > > What kind of virtual disk image are you using for the guest ? A > partition > > or a file - if the latter is it sparse, or non-sparse. Basically > sparse > > files will be horribly slow because every time the host OS has to > extend > > the sparse file to allocate real blocks it needs to do a journal sync > on > > the host FS. This destroys performance of I/O from the guest until the > > sparse file is fully-allocated. > > I'm using files. I've been using a command-line such as this for the > install: > > virt-install -m "00:16:3e:00:00:01" -n hostname -r 500 --vcpus=2 -f > /var/lib/xen/images/myhost.xen.img -s 4 --nographics -p -l > ftp://host/fc6/distro/i386/os -x "ks=http://kshost/ks.cfg"; > > Adding --nonsparse into the args looks like it fixes the speed issues > (albeit adds a bit of extra time right up front to allocate the entire > disk image). I imagine using partitions instead of files would be faster > altogether. I'll have to explore that option (files are just so nice to > ship around when needed). If pre-allocated, files should be within a few % of real partitions. > What does the "slower" here refer to? Slower up-front time to create the > image file? Yes, but the actual install will be faster since it wont > have to keep allocating more space for the disk image. Thoughts? Yes, upfront time will be longer due to the need to pre-allocate the disk, this should be more than offset by the faster install time. So I'd use --nonsparse as a general rule. Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=| -- Fedora-xen mailing list Fedora-xen@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-xen
