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Date:      Tue, 25 Mar 2014 09:12:09 +0100
From:      Borja Marcos <borjam@sarenet.es>
To:        Doug Ambrisko <ambrisko@cisco.com>
Cc:        "scottl@netflix.com" <scottl@netflix.com>, "Radford, Adam" <Adam.Radford@lsi.com>, "sean_bruno@yahoo.com" <sean_bruno@yahoo.com>, "Mankani, Krishnaraddi" <Krishnaraddi.Mankani@lsi.com>, "dwhite@ixsystems.com" <dwhite@ixsystems.com>, "Maloy, Joe" <Joe.Maloy@lsi.com>, "jpaetzel@freebsd.org" <jpaetzel@freebsd.org>, "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org>, "Kenneth D. Merry" <ken@kdm.org>, "McConnell, Stephen" <Stephen.McConnell@lsi.com>
Subject:   Re: LSI - MR-Fusion controller driver <mrsas> patch and man page
Message-ID:  <AE6FAC75-D2EA-457F-8654-2ECD57EDAA13@sarenet.es>
In-Reply-To: <20140324174519.GA30345@cisco.com>
References:  <e59396595152456dbcde63d48f70aa8f@BN1PR07MB247.namprd07.prod.outlook.com> <20140107181139.GC2080@cisco.com> <20140124185356.GA28724@ambrisko.com> <20140124190047.GA34975@ambrisko.com> <9c3fd2b15e9b4c2cb967519a3b7f98ad@BN1PR07MB247.namprd07.prod.outlook.com> <20140318143738.GA65955@cisco.com> <20140320235534.GA92797@cisco.com> <C698AC2A-06A7-4408-9790-20B69FAF31C6@sarenet.es> <20140321160954.GB99545@cisco.com> <5C32A3C7-B28B-4E69-9DF0-EE53181085F7@sarenet.es> <20140324174519.GA30345@cisco.com>

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On Mar 24, 2014, at 6:45 PM, Doug Ambrisko wrote:

> On Mon, Mar 24, 2014 at 09:03:43AM +0100, Borja Marcos wrote:
> |=20
> | On Mar 21, 2014, at 5:09 PM, Doug Ambrisko wrote:
> |=20
> | > Do you have a simple test case for that?  There were issues in the =
SCSI
> | > command translation which should have been fixed via switching it =
to use
> | > the CAM translation code.  Can you try it via a RAID volume of one =
disk?
> |=20
> | Yes, I tried all those possibilities. "syspd" devices, passthrough=20=

> | (same result, corrruption) and when creating single-disk RAID0 =
volumes=20
> | it worked, no corruption.
>=20
> Okay, so you don't have and simple test case to show this.  What are
> you currently doing?  I would think the syspd and the single disk =
RAID0
> should be very similar.  I'll take a look at that.

Yes, sorry for not being so explicit.

The server  I tried has a backplane, with 23 disks fitted. At first  I =
assumed it would work, so
I just created a raidz2 vdev  and begun running benchmarks. That's where =
I noticed  that it was
corrupting data badly.

The disks were set as "JBOD" with the Invader's built-in configuration =
tool and visible as mfisyspd drives.

So I reduced it to using a single disk. Choosing one of them at random, =
I did a newfs. Mounted, and executed
bonnie++. I got a panic after  some time. To avoid the inconvenience of =
panics, I moved to ZFS (single disk vdev)=20
so that I could still detect corruption.

The tests I did were:

- Disk in JBOD/syspd mode, accessed through /dev/mfisyspd -> corruption
- Disk in JBOD/syspd mode, passthrough enabled, accessed as /dev/daX -> =
corruption
- 1 disk RAID0 volume, accessed as /dev/mfid0 -> NO corruption

And I understand that syspd and RAID0 should be really different. I =
understand that it's a shallow layer
doing little more than passing through commands? I should read the =
driver thoroughly it seems... Pity there
are no available documents.

> | Just in case I tried with SSDs (Samsung EVO  840 and OCZ Vertex 4) =
and=20
> | Seagate SAS disks.
>=20
> So it seems generic.  Size of disk might be useful.


The Samsung are 1 TB, the OCZ are the 512 MB ones, and the Seagates are =
146 GB.=20
The SSDs (Samsung and OCZ) are SATA disks, the Seagate is SAS. The =
Seagate was corrupted as well in the
same test cases, so it doesn't seem to be linked to SATA-on-SAS or to =
TRIM. TRIM, anyway, doesn't work
on "mfisyspd" devices, which is a problem if you want to run ZFS on SSD =
disks.

> | Actually I think that converting passthrough disks to "mfisyspd" or =
an
> | equivalent is a bad idea, unless, of course, there's a compelling =
reason
> | I don't realize. For instance, if you are using SSDs you need access =
to
> | the TRIM command.
> |=20
> | So, if I can vote, I vote with arms and legs for "da" devices in =
case it's
> | a passthough.
>=20
> Nothing is planned to be removed from mfi.  However, LSI would like =
mrsas
> to be used on newer cards.  We've let people LSI know that people use
> the pass through mode and having the logical volumes come up as =
/dev/daX
> and pass through would be confusing.  Granted mrsas doesn't support =
pass
> through so that isn't a problem.

Pass through is a critical feature when you are running ZFS. I think =
it's a real problem
if the new driver (the only one that will support newer cards, I guess) =
won't support
pass-through.=20

And of course I know that you can just buy making sure that you get HBAs =
instead of
RAID cards, but  so many manufacturers bundle those RAID controllers in =
fixed  configurations
that it wouldn't be practical.

The ideal solution would be to have logical volumes come up as =
/dev/mfid, /dev/mrsas, /dev/mfisyspd
or whatever, and passthrough devices as real passthrough devices like =
/dev/da. That would avoid
confusion.

So, please, LSI, consider it. It would really add to the versatility of =
your cards and there's nothing
to lose.

> | It's not a pressing need, I installed a LSI2008 card and I connected =
the=20
> | SAS backplane to it, so for now the Invader
> | is a non-problem, but if it will help to run some tests with the mps=20=

> | driver I can certainly do it.
>=20
> The mps driver is a different thing, mrsas is LSI's replacement for =
mfi
> with newer cards.  So if you could try syspd and single RAID 0 test
> with mrsas that would be great to see if that shows the same pattern
> of syspd failing with mfi and passing with single RAID 0.  Again,
> the logical volumes will show up as /dev/da* with no pass through
> devices.  If I can reproduce the problem then I can look into here
> or others might be able to find the solution.

I'll try, thanks :)





Borja.






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