HP AutoRAID 12H manual Array resources?

section 1				hp storage white paper
gives 100X the data protection of traditional				environment changes. HP’s Virtual Array
RAID 5 and 10X the data protection of RAID 1.				Architecture tunes the array automatically, 24
Second: The HP Virtual Array stripes across all				hours per day. It is the hands-down winner in
the disks in the redundancy group. This involves				real-world performance. A better analogy1would
more disks but is not so different from any other				be to compare the multiple manual processes
RAID 1+0 implementation. Third: array striping				required to set the type, load the paper, and
is the way of the future. It’s faster and safer.				actually print books on the old-style printing
				presses with those of the automated printing
Question: Doesn’t all this “behind the scenes”				systems of our generation. Obviously, automation
movement of data require a huge performance				in printing presses adds to greater performance.
hit? Surely, the trade-off for virtual technology is				It works the same for arrays.
slow performance.				Question: Wouldn't striping the data across
Answer: Not true. For years, HP’s original
				such large RAID groups make the disk rebuild
virtual array,	the AutoRAID	Model 12H,	was
				times very long and take up a high percentage
used for HP’s	V-class TPC-C	benchmark	tests.
				of the array resources?
And today, HP Virtual Array products have been
				Answer: Because of HP’s RAID 5DP this is
used for the new rp8400 benchmark testing and
are scheduled to be used for the Superdome				practically a non-issue for HP Virtual Array
TPC-C tests. Remember, the HP Virtual Array				products. The HP Virtual Array’s RAID 5DP gives
mimics the policies of experienced system				each redundancy group 10x the protection of
administrators. Would an experienced system				RAID 1. RAID 5DP requires that 3 drives would
administrator do a reconfiguration of the array				have to fail before there would be data loss.
during a period of high workloads? No! And				Thus, even AFTER a drive fails, the data is STILL
neither would the HP Virtual Array. The HP Virtual				protected with the same degree of protection as
Array policy is to NOT perform the background				standard RAID 5. Finally, this means that a single
tuning operations when the array is under a				drive failure does not put the data at risk and
greater than 60% workload.				therefore does not require an emergency
				rebuild. The HP Virtual Array can take the time
Question: Isn’t manual always better than				and do the rebuild in the background without
automatic? In cars, manual transmissions give				impacting incoming I/Os. Also, the HP Virtual
better performance than automatic transmissions				Array will rebuild the RAID 1+0 data first since
because they give the driver more control over				that is the most vulnerable after a failure. In all
performance; likewise wouldn’t manual RAID				cases, data integrity is ensured and performance
configurations be better than HP’s Virtual Array				is preserved. No other array can make this claim.
Technology and its automatic RAID configurations?				Question: If your environment is totally stable,
Answer: Manual transmissions in cars would
				wouldn’t a manual configuration by an experienced
not give better performance if drivers were only
				system administrator result in better performance
allowed to shift gears once		and could never
				than one derived from the virtual array’s policies?
change them after that. In essence, this is what
				Answer: Let’s first admit it: Totally stable
you have with traditional disk arrays. You are stuck
with the initial configuration unless you bring the				environments are rare. But the answer is that if
array down and go through a time-consuming				the environment were totally stable, and if the
and complex	reconfiguration every time the			administrator configured the array absolutely

1.7