From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============1731918557182498671==" MIME-Version: 1.0 From: David Butterfield Subject: Re: [SPDK] RAID1E POC Status Date: Fri, 27 Sep 2019 14:50:37 -0600 Message-ID: In-Reply-To: 82C9F782B054C94B9FC04A331649C77AC58842DC@FMSMSX126.amr.corp.intel.com List-ID: To: spdk@lists.01.org --===============1731918557182498671== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On 9/22/19 9:42 AM, Luse, Paul E wrote: > Still just a POC and a lot of work to do before we'd consider production = worthy> if we decide to continue with it (I'll work on putting a list toget= her over the next few weeks). Are any of the Linux kernel RAID implementations considered good? I have DRBD 9.0 running in usermode under SPDK as shown in this diagram: https://raw.githubusercontent.com/DavidButterfield/spdk/tcmu-runner/spd= k_drbd.pdf One possibility would be to port a kernel RAID module into the spot occupie= d by DRBD in the diagram. The "port" of DRBD to run in usermode changes fewer than a dozen lines of c= ode from the original source in the LINBIT repository. Rather than changin= g the source code from the DRBD kernel module, its expected environment is = simulated around it. (This is intended to make it easier to update the use= rmode port to newer versions of the application as they appear.) I did the same thing with SCST a couple of years ago. I would expect the s= ame to be possible for a kernel RAID module. It won't just "drop in", beca= use the set of emulated kernel functions has to be expanded to include what= ever the RAID module uses that isn't already covered by the existing ports = of SCST and DRBD. I estimate it would take me one to two months of full-ti= me work to get a kernel RAID module up and running well enough to be tested= and used for experimentation. Regards, David Butterfield --===============1731918557182498671==--