Why HDTach shows RAID0 slower than JBOD on 3ware 3W-7450?

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hh

I connected 4 units Seagate ST340016A ATA100 to a 3W-7450 (firmware &
Windows driver 7.7.0) and compared read & write speeds between RAID0 &
JBOD with HDTach 2.7 on unformatted drives, but very puzzled to find
RAID0 (4-drive striped 1024K write-cache enabled) slower than JBOD
speeds.

Here are the test results:

RAID0 Access R.Burst R.Max R.Min R.Avg W.Max W.Min W.Avg CPU%
test#1 14.0 32.9 27.4 14.5 20.6 19.5 9.2 16.0 22.5
test#2 13.9 33.0 27.8 13.8 20.7 19.6 11.9 16.0 22.8
test#3 13.9 32.9 28.3 13.5 20.4 19.2 12.8 16.1 24.0
avg 13.9 32.9 27.8 13.9 20.6 19.4 11.3 16.0 23.1

JBOD Access R.Burst R.Max R.Min R.Avg W.Max W.Min W.Avg CPU%
hdd#1 14.6 34.2 33.3 16.1 25.2 20.3 13.5 17.0 25.6
hdd#2 14.7 34.7 33.2 19.9 25.0 20.3 12.4 17.0 22.7
hdd#3 14.9 33.7 33.1 17.9 24.9 20.5 13.2 16.9 24.7
hdd#4 14.2 33.9 32.5 15.7 23.3 20.5 13.2 16.9 23.1
avg 14.6 34.1 33.0 17.4 24.6 20.4 13.1 17.0 24.0

Morever, the above JBOD speeds with the 4 drives connected to 3W-7450
are even slower than JBOD speeds with the same 4 drives connected
directly to the motherboard's ATA100 ports.

What's wrong? Please advise, thanks!
 
I connected 4 units Seagate ST340016A ATA100 to a 3W-7450 (firmware &
Windows driver 7.7.0) and compared read & write speeds between RAID0 &
JBOD with HDTach 2.7 on unformatted drives, but very puzzled to find
RAID0 (4-drive striped 1024K write-cache enabled) slower than JBOD
speeds.

Here are the test results:

RAID0 Access R.Burst R.Max R.Min R.Avg W.Max W.Min W.Avg CPU%
test#1 14.0 32.9 27.4 14.5 20.6 19.5 9.2 16.0 22.5
test#2 13.9 33.0 27.8 13.8 20.7 19.6 11.9 16.0 22.8
test#3 13.9 32.9 28.3 13.5 20.4 19.2 12.8 16.1 24.0
avg 13.9 32.9 27.8 13.9 20.6 19.4 11.3 16.0 23.1

JBOD Access R.Burst R.Max R.Min R.Avg W.Max W.Min W.Avg CPU%
hdd#1 14.6 34.2 33.3 16.1 25.2 20.3 13.5 17.0 25.6
hdd#2 14.7 34.7 33.2 19.9 25.0 20.3 12.4 17.0 22.7
hdd#3 14.9 33.7 33.1 17.9 24.9 20.5 13.2 16.9 24.7
hdd#4 14.2 33.9 32.5 15.7 23.3 20.5 13.2 16.9 23.1
avg 14.6 34.1 33.0 17.4 24.6 20.4 13.1 17.0 24.0

Morever, the above JBOD speeds with the 4 drives connected to 3W-7450
are even slower than JBOD speeds with the same 4 drives connected
directly to the motherboard's ATA100 ports.

What's wrong? Please advise, thanks!
Click to expand...

Nothing is wrong with your system. HDTach simply gives wrong results
when you test it on Raid arrays. This is a known issue. (know to the
users, not sure if the maker has acknowledged the bug)

Marc
 
Nothing is wrong with your system. HDTach simply gives wrong results
when you test it on Raid arrays. This is a known issue. (know to the
users, not sure if the maker has acknowledged the bug)

Marc
Click to expand...

What software can benchmark RAID correctly? Thanks!
 
Try HDtach 3.0 ?


Nothing is wrong with your system. HDTach simply gives wrong results
when you test it on Raid arrays. This is a known issue. (know to the
users, not sure if the maker has acknowledged the bug)

Marc
Click to expand...
 
RAID0 & JBOD configurations remain unchanged, here are HDTach 3.0.1
test results:

RAID0 Access R.Burst R.Avg CPU%
test#1 14.3 45.9 30.8 10.0
test#2 14.1 46.8 30.9 6.0
test#3 14.3 45.8 30.7 6.0
avg 14.2 46.2 30.8 7.3

JBOD Access R.Burst R.Avg CPU%
hdd#1 14.8 46.3 35.2 8.0
hdd#2 14.7 46.0 33.5 0.0
hdd#3 15.0 44.7 33.6 22.0
hdd#4 14.6 43.9 31.1 0.0
avg 14.8 45.2 33.4 7.5

If such benchmarks are correct, isn't RAID0 with 3ware 7450 a total
waste of time and money?

Any other ideas? Thanks!
 
I would not rely exclusively on HDTach for performance benchmarking.
What do you plan on using RAID configuration (OS / Application) for?
Suggested answers will depend on that. There is a lot of performance metrics
for which storage tuning guidlines vary a lot. Take into account size of
your data files, read/write ratio, random/sequential access ratio, block
size, average concurrent IO's. etc...
Also, you might find the following article interesting:
http://www.storagereview.com/articles/200406/20040625TCQ_1.html
 
RAID0 & JBOD configurations remain unchanged, here are HDTach 3.0.1
test results:

RAID0 Access R.Burst R.Avg CPU%
test#1 14.3 45.9 30.8 10.0
test#2 14.1 46.8 30.9 6.0
test#3 14.3 45.8 30.7 6.0
avg 14.2 46.2 30.8 7.3

JBOD Access R.Burst R.Avg CPU%
hdd#1 14.8 46.3 35.2 8.0
hdd#2 14.7 46.0 33.5 0.0
hdd#3 15.0 44.7 33.6 22.0
hdd#4 14.6 43.9 31.1 0.0
avg 14.8 45.2 33.4 7.5

If such benchmarks are correct, isn't RAID0 with 3ware 7450 a total
waste of time and money?

Any other ideas? Thanks!
Click to expand...

You could take a look at other benchmark tools used by review sites.
But really, you should just forget about HDTach completely. The
results are bogus, and I can prove that on my own system with
performance monitor.
(Tested it a few weeks ago because someone else noticed the same
problems)

But instead of benchmarks tools you can probably also get enough
information with performance monitor.

What applications will you be using the configuration for?

Marc
 
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