On Thu, Jun 23, 2016 at 09:50:11AM -0700, Preston L. Bannister wrote: > Daniel, Thanks. Looking for a sense of direction. > > Clearly there is some range of opinion, as Walter indicates. :) > > Not sure you are get to 100% direct connection to QEMU. When there is > dedicated hardware to do off-board processing of the connection to storage, > you might(?) be stuck routing through the nova-compute host Linux. (I am > not an expert in this area, so I could easily be wrong.) This sort of > hardware tends to be associated with higher-end "enterprise" storage and > hosts (and higher cost). The storage guys are in the habit of calling these > "HBA adaptors" (for high-bandwidth) - might just be a local thing.
nit: HBA == Host Bus Adapter :) > > I *suspect* that higher cost will drive most cloud deployments away from > that sort of specialized hardware. In which case the direct-connect to QEMU > model should (mostly?) work. (My non-expert guess.) > > > > On Thu, Jun 23, 2016 at 9:09 AM, Walter A. Boring IV <[email protected]> > wrote: > > > > > volumes connected to QEMU instances eventually become directly connected? > > > > Our long term goal is that 100% of all network storage will be connected > >> to directly by QEMU. We already have the ability to partially do this with > >> iSCSI, but it is lacking support for multipath. As & when that gap is > >> addressed though, we'll stop using the host OS for any iSCSI stuff. > >> > >> So if you're requiring access to host iSCSI volumes, it'll work in the > >> short-medium term, but in the medium-long term we're not going to use > >> that so plan accordingly. > >> > > > > What is the benefit of this largely monolithic approach? It seems that > > moving everything into QEMU is diametrically opposed to the unix model > > itself and > > is just a re-implementation of what already exists in the linux world > > outside of QEMU. > > > > Does QEMU support hardware initiators? iSER? > > > > We regularly fix issues with iSCSI attaches in the release cycles of > > OpenStack, > > because it's all done in python using existing linux packages. How often > > are QEMU > > releases done and upgraded on customer deployments vs. python packages > > (os-brick)? > > > > I don't see a compelling reason for re-implementing the wheel, > > and it seems like a major step backwards. > > > > > >> Xiao's unanswered query (below) presents another question. Is this a > >>> site-choice? Could I require my customers to configure their OpenStack > >>> clouds to always route iSCSI connections through the nova-compute host? > >>> (I > >>> am not a fan of this approach, but I have to ask.) > >>> > >> > > > In the short term that'll work, but long term we're not intending to > >> support that once QEMU gains multi-path. There's no timeframe on when > >> that will happen though. > >> > >> > >> Regards, > >> Daniel > >> > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: [email protected]?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
