Re: [Xen-users] Passthrough of PCIe RAID card

[Atom2 <ariel.atom2@xxxxxxxxxx>]

Am 29.08.14 00:53, schrieb Mike Reardon:
> Hello,
>
> I am curious if I add a PCIe RAID card to my system, if Xen will allow
> me to pass it through to a domU so that the guest can have native disk
> operations.
>
> The domU in question is a Windows HVM guest that I am using as a PVR.  I
> tried using the GplPv drivers in windows but kept getting XenVbd errors
> and resets in the event logs causing video playback pauses, so I'm
> currently serving the video storage volume to the guest via iSCSI, which
> isn't exactly ideal.  I'm hoping that I can just add in the RAID card
> and a couple disks and have native I/O, but I don't know if that is
> going to work.  I'm mainly concerned that the card won't be properly
> initialized when the guest starts, or that there will be some sort of
> conflict with the LSI RAID card that the server is already using.
>
> Does anyone have any experience in using a RAID card in this way?  Any
> insights that anyone could provide would be greatly appreciated as I
> haven't yet decided whether I will buy the card or not.
I am using an IBM ServeRaid M1015 (reflashed to an LSI9211-8i, so no 
longer a real RAID card) on XEN 4.3.2. My dom0 OS is gentoo linux 
(kernel 3.15.8-hardened) and the guest domU is FreeBSD 10.0 (x64, 
therefore HVM mode with PV drivers for a block- and net devices). The 
reason for the passthrough is that I use ZFS on FreeBSD (raidz2 with 4 
2TB disks). ZFS prefers to have direct access to the drives. This 
approach also ensures that SMART monitoring for the disks works in the domU.
Both my motherboard and my processor (XEON E3-1260L) support VT-d.

The only requirement in FreeBSD was to disable MSI-X for the IBM 
ServerRaid card and stick to MSI interrupts. I don't know whether that's 
performance relevant, but I am sure somebody else is able to comment on 
that aspect.
So far I have not seen any other issues, but still need to do some 
stress testing one day.
Regards Atom2

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