Lars Marowsky-Bree wrote:
On 2009-06-02T22:07:17, Zhang Weiwu
wrote: As far as I know if the hard disk of the guest os is an image file on the host OS, the host OS treats it as a file and offer to cache it in the main memory. However if vmplayer access a partition or harddisk it is not cached by the host OS's file system. That might make it even slower. Unless of course the database is in particular on a raw device that is directly accessed from the guest OS, as Sandy pointed out.
The caching doesn't make a difference, as it is not really different.
The question itself is not relevant. Fact is that performance will increase a lot if you use a raw device. How ineffective VMWare disk access within a VM is I can see even on my small server at home. The server has a raid5 with 5 disks on a 3ware controller. Even if I only use a VM as a normal user workstation (for email/browers etc with few write access) the iowait increases a lot. Before I installed vmware i practically never had iowait on my server, now I see iowait all the time in my munin graphs. Even at our company on our ESX Cluster with the VMFS on a SAN I have problems with some VMs due to lacking i/o performance. :-(( If you want to be happy with VMs you will have to optimize I/O as good as possible. :-/ -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org