> On 01 Aug 2016, at 15:12, O. Hartmann <ohartman_at_zedat.fu-berlin.de> wrote: > > First, thanks for responding so quickly. > >> - The third option is to make the driver expose the SAS devices like a HBA >> would do, so that they are visible to the CAM layer, and disks are handled by >> the stock “da” driver, which is the ideal solution. > > I didn't find any switch which offers me the opportunity to put the PRAID > CP400i into a simple HBA mode. The switch is in the FreeBSD mfi driver, the loader tunable I mentioned, regardless of what the card firmware does or pretends to do. It’s not visible doing a "sysctl -a”, but it exists and it’s unique even. It’s defined here: https://svnweb.freebsd.org/base/stable/10/sys/dev/mfi/mfi_cam.c?revision=267084&view=markup (line 93) >> In order to do it you need a couple of things. You need to set the variable >> hw.mfi.allow_cam_disk_passthrough=1 and to load the mfip.ko module. >> >> When booting installation media, enter command mode and use these commands: >> >> ----- >> set hw.mfi.allow_cam_disk_passthrough=1 >> load mfip >> boot >> ——— > > Well, I'm truly aware of this problemacy and solution (now), but I run into a > henn-egg-problem, literally. As long as I can boot off of the installation > medium, I have a kernel which deals with the setting. But the boot medium is > supposed to be a SSD sitting with the PRAID CP400i controller itself! So, I > never be able to boot off the system without crippling the ability to have a > fullspeed ZFS configuration which I suppose to have with HBA mode, but not > with any of the forced RAID modes offered by the controller. Been there plenty of times, even argued quite strongly about the advantages of ZFS against hardware based RAID 5 cards. :) I remember when the Dell salesmen couldn’t possibly understand why I wanted a “software based RAID rather than a robust, hardware based solution” :D At worst, you can set up a simple boot from a thumb drive or, even better, a SATADOM installed inside the server. I guess it will have SATA ports on the mainboard. That’s what I use to do. FreeNAS uses a similar approach as well. And some modern servers also can boot from a SD card which you can use just to load the kernel. Depending on the number of disks you have, you can also sacrifice two to set up a mirror with a “nomal” boot system, and using the rest of the disks for ZFS. Actually I’ve got an old server I set up in 2012. It has 16 disks, and I created a logical volume (mirror) with 2 disks for boot, the other 14 disks for ZFS. If I installed this server now I would do it different, booting off a thumb drive. But I was younger and naiver :) Borja.Received on Mon Aug 01 2016 - 11:30:09 UTC
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