Hi All, On Thu, 9 Nov 2023, 13:19 Robert Hudson, <hud...@gmail.com> wrote:
> I largely agree with Luke. Given you're on a dedicated iSCSI network, > keep it simple. DCB and other services will only add things that you'll > later need to troubleshoot and eliminate as the root cause of network > issues on your iSCSI network when they invariably happen (it's rare that > I've come across a well and consistently configured iSCSI network, and I've > been playing in that space since the mid 2000s). Chances are your > OS/hypervisor vendor of choice publishes best practices for how to > configure DCB - but as noted, DCB is specifically there to deal with > converged networks (where your iSCSI traffic is sharing an ethernet fabric > with other traffic types), and you don't seem to have that situation. > > Jumbo frames help in busy iSCSI networks by increasing throughput - but > you need to make sure every device from one end of the communications to > the other fully supports it. Again, follow vendor advice here. Getting > this wrong can cause all sorts of "fun". > Related to MTUs, etc., people here might be interested in a presentation on the topic I did at NZNOG in March. MTUs, MRUs, PMTUs https://www.youtube.com/live/_D03z8LrauU?si=Mr5hadabWXePhCjk&t=1971 > Flow control, buffer tuning (large buffers tend to help with iSCSI > traffic), etc, can all help to eke out a few more small percentage points > of performance, but again, the further you drift from the KISS principle, > the more fun you're likely to have troubleshooting later. > Strongly agree with KISS (foreshadowing the advice at the end of the presentation.) > Above all - set and document policy in all things, audit against that > policy both at initial setup and for drift during the lifecycle of the > environment. > > On Thu, 9 Nov 2023 at 12:20, Luke Iggleden <l...@iggleden.com> wrote: > >> Hi Andres, >> >> Unless you are running other services on the switch it's not useful. >> >> Typically these are the only useful changes: >> >> Jumbo Frames (YMMV), depends on vendor. >> >> Flow Control on (so hosts can issue back off - hopefully without dropping >> frames) >> >> Depending on the switch, buffer tuning. >> >> Don't use control plane things, like MLAG, Stacking, STP, etc etc. Flat >> fabric. >> >> >> Cheers, >> >> Luke Iggleden >> >> >> On 9/11/2023 11:14 am, Andres Miedzowicz wrote: >> >> Hello everyone, >> >> >> >> I wanted to get some opinions on the use of DCB and its associated >> protocols in a storage-only (iSCSI), non-converged network. Any thoughts >> about the pros and cons of enabling DCB in a scenario where 100% of the >> traffic on a switch is bi-directional iSCSI storage (virtual machines and >> backups)? >> >> >> >> Thanks in advance. >> >> >> >> Andres >> >> _______________________________________________ >> AusNOG mailing >> listAusNOG@lists.ausnog.nethttps://lists.ausnog.net/mailman/listinfo/ausnog >> >> _______________________________________________ >> AusNOG mailing list >> AusNOG@lists.ausnog.net >> https://lists.ausnog.net/mailman/listinfo/ausnog >> > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net > https://lists.ausnog.net/mailman/listinfo/ausnog >
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