Are you running the latest drivers and have you tried ajusting the disk under disk manager in control panel
enable write caching on the disk
enable advanced perforance
CT
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RAID 0 vs 1 performance in Windows 7 + Velociraptors
See the screenshots.
Here is what I get with 2 different setups of dual 300gb Velociraptor drives. I was very disappointed in the RAID 1 performance on reads. I used the defaults of the 3ware 9650SE-4LPML (64k stripes in the RAID0). No other tuning was done, both fresh installs of Win7. Write cache enabled.
Any idea why read performance is so bad with the RAID1? This is not always so, depending on the hardware and who you ask.
- HDTune-Benchmark-AMCC----9650SE-.png
- 64 KB
RAID1
- HDTune-Benchmark-AMCC----9650SE-.png
- 118 KB
RAID0 64k stripe
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Answers
what were you expecting. RAID0 reads from two disks in essence so it has a much higher possible throughput than any other version of RAID. That's the whole point of RAID0 performance. RAID1 adds significant redundancy but you are basically only reading from a single disk at a time. so you aren't seeing any benfits from the RAID configuration on reads like you are with RAID0.
Yes, along with the latest firmware, I am using the latest 3ware driver.
I don't want to fiddle with write caching, this is a read test benchmark so it should not matter.
Not sure what you mean about advanced performance. I used identical setups, no tweaking from the OS level.
My question really is not how to tune anything from the OS side. I ran benchmarks on the RAID volume as it is presented to the OS by the card. This is how it performs in comparison.
Apparently the card is not doing the sort of parallel reading I would have assumed when using mirroring and my research online shows that these RAID1 numbers really do not differ from a single drive performance.
>>what were you expecting.
Better read performance from a RAID1.
>>RAID1 adds significant redundancy but you are basically only reading from a single disk at a time
I disagree. RAID1 can read from both disks. Historically, RAID1 is touted for its ability for parallel, interleaved read performance. By the looks of this benchmark, this is not happening with this card. I'm not a RAID newbie, I'm looking for a little more insight.
My feeling is that perhaps this specific RAID card is just not that smart. Notice some of the statistical outliers on the RAID1 graph on the random seek times. Those don't exist in the RAID0. That does not make sense to me.
The numbers appear to be pretty normal...
I think you may be overanalyzing the performance in a RAID 1 array (or underanylzing for that matter)...
Yes, RAID 1 can read from both disks and therefore should have faster reads...and it does, but its a "split seek", and its only faster in certain situations. Your controller is going to ask each hard drive for data, and it'll use whichever can respond first...but its still looking at the same data. Think more about the mechanics...How does it know when to split up the data? When does it put that data back together? Its not a straight road of data, they're not in the same spot on both drives...its pretty complicated. Theres obviously much more to it than that and some controllers are better than others when splitting up the data, but its more dependant on the situation.
http://www.usenix.org/even
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As for your outliars, they look like it was when the disk was being used for something else. Try copying a large file from the RAID 1 to the RAID 0 and vice versa....take a look at your times.
- HD-Tune-RAID-0.png
- 77 KB
36GB SAS drives
Thanks for the comments. Yes, it seems my expectations were too high for RAID-1. I've never actually profiled RAID-1 before as I usually choose it solely for the redundancy. I have seen good numbers from RAID-10 in the past.
I also tried a 3rd option with RAID-0 using 256k stripes and the read performance is even more improved, as I expected, though a little jagged due to the access patterns being optimized for larger single drive sequential reads. The access time suffered by a few fractions of a ms, but the reads overall are drastically improved, especially for the first 50% of the drive. I try to keep my drives < 50% full for best performance.
I don't recommend RAID-0 but I needed the performance and I had to back into this old Dell Precision 390 PC because my other motherboard would not see more than 4GB RAM no matter the combination of chips I tried. The Dell case will not fit more than 2 drives easily, however, so its either RAID-0 or 1 for now and I'm doing daily Ghost backups.
I think I'll be buying a new case and motherboard so I can add more disks and switch to RAID-5 or 10 and keep my 8GB RAM. I would like to go solid state but my space requirements are too high for what I can afford with SSD. Maybe next year. :)
Yes, I would have to agree with some comments already made.
Keep in mind that RAID 1 is not for performance, but for redundancy. Unfortunately it's difficult and expensive trying to have the best of both worlds. If you want speed use RAID-0, If you want Redundancy use RAID-1. If you want a little of both, add an additional drive and make it a RAID-5. If you want all the benefits of both worlds you would have to utilize RAID-50, which would be overkill for a Desktop or Workstation. For Data Recovery services and RAID Recovery take a look at http://www.datanalyzers.co
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by: mrjoltcolaPosted on 2009-07-23 at 12:59:39ID: 24929361
FYI I am using the latest firmware, I flashed the RAID card prior to the installs.