Someone can explain me good difference between file and tap:aio, pros and cons, and also with all possibility with blktap2? Thanks for any response -- View this message in context: http://old.nabble.com/Difference-between-file-and-tap%3Aaio-tp28191044p28191044.html Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, Apr 09, 2010 at 07:13:22AM -0700, Fantu wrote:> > Someone can explain me good difference between file and tap:aio, pros and > cons, and also with all possibility with blktap2? Thanks for any response >file: uses dom0 kernel page cache, and thus might give better performance than phy: or tap:aio:, but it''s also more insecure because of the caching. tap:aio: uses direct IO, so it bypasses dom0 kernel caches, and works like phy: in that sense. blktap1 provides also other modes than :aio, like: qcow, but those were not very stable or fast, so blktap2 was developed. for blktap1 see: http://wiki.xensource.com/xenwiki/blktap . blktap2 also has vhd image support including snapshots and cloning. See here: http://wiki.xensource.com/xenwiki/blktap2 . -- Pasi _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Would file: really have a better performance than phy: ? I am planing to use a own partition for my Windows HVM Domain, cause in the fact you going to use a Filesystem in a filesystem, so this need more time than only "one" filesystem i think..... Am 09.04.2010 16:24, schrieb Pasi Kärkkäinen:> On Fri, Apr 09, 2010 at 07:13:22AM -0700, Fantu wrote: > >> Someone can explain me good difference between file and tap:aio, pros and >> cons, and also with all possibility with blktap2? Thanks for any response >> >> > file: uses dom0 kernel page cache, and thus might give better performance than phy: or tap:aio:, > but it''s also more insecure because of the caching. > > tap:aio: uses direct IO, so it bypasses dom0 kernel caches, and works like phy: in that sense. > > blktap1 provides also other modes than :aio, like: qcow, but those were not very stable or fast, > so blktap2 was developed. for blktap1 see: http://wiki.xensource.com/xenwiki/blktap . > > blktap2 also has vhd image support including snapshots and cloning. > See here: http://wiki.xensource.com/xenwiki/blktap2 . > > -- Pasi > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Fajar A. Nugraha
2010-Apr-13 02:39 UTC
Re: [Xen-users] Difference between file and tap:aio
On Tue, Apr 13, 2010 at 4:13 AM, Tegger <xen@tegger.de> wrote:> Would file: really have a better performance than phy: ?If your working set is smaller than dom0 memory, then yes. This is due to dom0 caching effect.> I am planing to use > a own partition for my Windows HVM Domain, cause in the fact you going to > use a Filesystem in a filesystem, so this need more time than only "one" > filesystem i think.....functionality-wise, there''s nothing "wrong" about have a domU filesystem on top of a disk image file on top of dom0 filesystem. I''d stick with phy:/ though, due to (generally) more performance and reliablity. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users