----- Original Message ----- > From: "Sven Kieske" <[email protected]> > To: [email protected] > Sent: Thursday, October 23, 2014 4:31:02 PM > Subject: [ovirt-devel] how (inefficient) does vdsm import sparse disks in > local storage(file based) data domain? > > Hi, > > I might be totally mistaken, so please tell me first if I understand > the process: > > when vdsm imports a template from an export domain to local storage, > according to my "ps" output, vdsm copies sparse templates using "dd": > > vdsm 14378 0.3 0.0 59032 4424 ? S<l 14:43 0:05 \_ > /usr/bin/qemu-img convert -t none -f raw > /rhev/data-center/d6ec1bb0-43ce-4e09-9a7a-e54f9779af64/4ed22092-e961-4e04-b77b-2648ad21f83a/image > vdsm 17291 0.0 0.0 8344 608 ? D< 15:14 0:00 \_ > /bin/dd iflag=direct > if=/rhev/data-center/mnt/$REDACTED:_home_iso/e7b8f2e2-b9f7-493c-96b5-33bfb091d0ba/dom_md/metadata > bs=4096 count=1 > > If this is correct I have some questions regarding this behaviour: > > I understand that "dd" is "rock solid" works everywhere and for maybe > every storage/format combination and thus was maybe chosen to do the > work. > > But if I'm right and I have a 100 GB sparse disk which actually > uses just 1 GB "dd" will copy the whole 100 GB over network, which > is really not efficient at all.
We have this patch for next version: http://gerrit.ovirt.org/33355 > > So here's my proposal (if I do not have any mistakes in the above): > > at least make a: > tar -cpSvf disk.tar /path/to/disk > and than "dd" this over the network, because tar _can_ handle sparse > files. > > Of course any other more efficient mechanism would be okay too. > > If my observation is right, and the project think it's worth > to implement such a thing I would create an RFE for this Please do > and I also would like to help code this (in my leisure time). > > PS: I did observe this behaviour on ancient > ovirt 3.3 with vdsm version: vdsm-4.13.4-0.el6.x86_64 > but I didn't see anything in release notes which > changed this behaviour. > > -- > Mit freundlichen Grüßen / Regards > > Sven Kieske > > Systemadministrator > Mittwald CM Service GmbH & Co. KG > Königsberger Straße 6 > 32339 Espelkamp > T: +49-5772-293-100 > F: +49-5772-293-333 > https://www.mittwald.de > Geschäftsführer: Robert Meyer > St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen > Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen > _______________________________________________ > Devel mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/devel _______________________________________________ Devel mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/devel
