From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: Date: Wed, 23 Apr 2008 19:40:40 -0500 From: "Eric Van Hensbergen" To: "Fans of the OS Plan 9 from Bell Labs" <9fans@9fans.net> In-Reply-To: <371bee37a941420e21ffaf97c5e192b7@quanstro.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <371bee37a941420e21ffaf97c5e192b7@quanstro.net> Subject: Re: [9fans] new lguest port available Topicbox-Message-UUID: 99343be8-ead3-11e9-9d60-3106f5b1d025 On Wed, Apr 23, 2008 at 7:29 PM, erik quanstrom wrote: > >> just put it up on a tee: why not use aoe? > >> > > > > The problems of disk I/O are largely a focus issue -- all this stuff > > is pretty new and they focused on the network mechanisms first because > > those were the ones where the competition has published the most > > compelling benchmarks. The disk stuff will get tuned out and will > > likely outperform network for I/O. As an example, 9P directly over > > virtio beats NFS/TCP/virtio-net by 70% without cacheing or > > optimization in 9P (which is usually the opposite case on > > unvirtualized hardware due to cacheing and what not). > > i wouldn't think that you could tune out rotational latency. 8.4ms is > pretty much forever when you're counting nanoseconds. > > since aoe can do wirespeed (120ms/s) on typical physical gige > chipsets i would think it would have no trouble keeping up with > spinning media. especially when not handicapped by having to > actually stuff bits through a phy. > You on the wrong portion of the problem -- the disk solution they have is effectively AOV (ATA over Virtio), you aren't going to do better by putting a virtual network driver in between. They just have to tune their userspace gateway for disk access -- they put a lot of work into making the virtio<->tun/tap gateway really efficient and I think they are just using the crappy Qemu block device at the moment. Once they short-out the gateway between the guest-virtio channel and the in-kernel block driver it'll be much faster than tunneling AOE over the network device to the host. Now - if you are talking about supporting an off-server CORAID storage array -- then you should absolutely go AOE, but I think he was talking about talking between guest and host partitions on his laptop in which case you are adding extra layers for nothing. -eric