On 17 Jun 2015 at 15:36:13, Paul Sture ([email protected]) wrote: On 17 Jun 2015, at 14:03, Perttu wrote:
> On 17 Jun 2015 at 14:43:27, Paul Sture ([email protected]) wrote: >> In an office environment where the majority of files are docx, >> xlsx, >> pptx or their equivalents in non-MS Office products, they are >> already >> compressed, so there's little point in applying compression at the >> file >> level. This is easily demonstrated via "unzip -l" on one of those >> files. >> >> File fragmentation is also an issue (I'm thinking of Windows here). >> If >> the guest system is unaware that its files are on a host system, >> there >> may well be a substantial CPU overhead dealing with what it thinks >> are >> fragmented files because; it's not just a matter of disk head >> movement, >> the guest OS has to handle the mapping to all those file >> fragments. > > Do you mean that Windows might do automatic reordering on the fly if > it > thinks files are too fragmented? No, I'm thinking of the fragmentation itself, which occurs naturally in Windows as files are created and deleted. Windows has to manage the fact that files are fragmented and that can be CPU intensive. This is a little known overhead on top of the physical disk head movement associated with file fragmentation on traditional disks. I'd better explain where I'm coming from here. Back in the day I was using VMS, and that has monitoring tools which show the amount of CPU involved in mapping to fragmented files. That mapping happens in kernel mode, which has the highest priority, so an unprivileged user working with badly fragmented files could severely affect performance for everyone else. Yes CPUs are a lot faster nowadays so it should be less of an issue, but it's still something to be aware of. FWIW I have Windows 8.1 running under VMware Fusion and that will try to expand the sparse disk image its running in to its full extent each time I fire it up (VMware Fusion has a facility for reclaiming that space, which I do run to save disk space). I haven't seen this issue with and of the Windows Server variants I've run. -- Paul Sture Thanks, that’s good to know. I’m planning on running Windows 7 as a guest to reduce OS costs for light services that don’t need any Windows Server functionality. -Perttu ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
