[resolved, naively] Re: geom vs ich through ar device - benchmarks?

[Scott Long]

Howard Goldstein wrote:
> Howard Goldstein wrote:
>> Has anyone done any benchmarks in desktop or server environment
>> comparing geom with an ICH controller through the ar device in RAID1
>> service?  Teh google, it seems to pick up grammar school math
>> assignments lots of what may be relevant hits for fortunate speakers of
>> German :(
> 
> In case it may help someone else I've some benchmarks to share.  These
> are trivial and naive benchmarks since they test only one case which
> probably is the worst case for geom.
> 
> Testbed: Pair of WDC3200AAKS 320gb SATA, freshly newfsd 10gb filesystem
> mounted with softupdates, remounted after each test
> P4 @ 3ghz on a P4P800 in 6.2-STABLE, single user mode, ICH5R controller
> detects these SATA-II drives inexplicably as SATA-I
> 

ICH5 only support SATA-1.

> Naive test:  dd if=/dev/zero of=/fsundertest/tstfile bs=1m count=1000
> *not including buffered stuff unwritten, the test simply reported dd's
> idea of the transfer time*, and then the other way where it doesn't matter
> 
>  In firmware's RAID1                       Using the awesome gmirror
> write 1gb: 13.275                             13.7
> rd         12.9                               13.8
> 
> Of course after this I used gmirror...

Just so we're clear, the ICH5 doesn't have any firmware and doesn't
actually do any RAID operations.  What is has is hook into the system
BIOS during boot.  That hook allows the BIOS to do RAID-like operations
during boot, until the OS takes over control of the devices.  After
that, it's up to the OS to do all the RAID work.  The 'ar' driver is
still software RAID, just like gmirror.  What you've effectively done
merely compare the performance of one software RAID stack to another.
That's certainly an interesting comparison, but maybe not exactly what
you had in mind.

Scott