From robroy Mon Aug  1 12:54:22 2016
Date: Mon, 1 Aug 2016 12:54:22 -0700 (PDT)
From: Robroy Gregg
To: BSDNow
Subject: H/W RAID [LSI 9268-8i]:  UFS or ZFS?


Good day Kris and Allan!

I've split my question in to a quick edition and a detailed edition, in 
case the details are too long to read during your show.


Quick Edition
==========================================================================

If stuck with eight disks on an LSI 9268-8i (hardware RAID), which option 
is more likely to keep data safe and available:  A:  ZFS RAIDz2 on eight 
LSI RAID 0 virtual disks, or B:  UFS on one LSI RAID 6 virtual disk?


Detailed Edition
==========================================================================

A comrade and I would like to use ZFS on disks attached to an LSI 9268-8i, 
which has no IT mode firmware, and no JBOD mode.  'seems that a single 
RAID 0 virtual disk for each physical disk's as close as it gets.

This card's cache is set to write-through mode, and its patrol scrub is 
disabled.  The card has no BBU.

On page six of FreeBSD Mastery: ZFS, I read, "Do not use a hardware RAID 
controller.  Ever."

Two pages later, I read, "If you're condemned to use hardware RAID, 
probably because you were a very bad person in a previous life, present 
the operating system with single disks. If the RAID controller insists on 
formatting each drive as RAID-0, you're stuck."

Having read this--especially the first part--we spent several days trying 
hard to replace the 9268-8i with a 9211-8i.  Yet our computer refuses to 
recognize the new card; it only accepts the 9268-8i.  This is a Hitachi 
CR220H; the same 9211-8i worked fine in a Supermicro, but we have to use 
the Hitachi.

Given that we're stuck with the 9268-8i, which of these two options is 
most likely to keep our data safe and available long-term?

    A]  ZFS:  make an LSI RAID 0 virtual disk for each physical disk,
        then use the virtual disks for a RAIDz2 vdev.

    B]  UFS:  make a single LSI RAID 6 virtual disk, then use UFS
        on top.

I opened this FreeBSD Forums thread.  So far, all respondents who chose 
between these options, chose UFS (B) over ZFS (A).  I'd love to know your 
opinion.

    https://forums.freebsd.org/threads/57112/

Thanks so much!
Robroy

Robroy Gregg
Salinas, California