Does software RAID 1 (mirroring) in Windows 7 improve read speeds?

I'd like to set up RAID 1 to help protect my important documents (yes, yes, I know it's not a backup), but performance is also important to me. As I understand it, RAID 1 should theoretically be able to improve my read speeds by n times, where n is the number of disks.

Is Windows 7 able to get this boost? I haven't been able to find out this information anywhere.

  • Depends on the raid controller and model of hard discs what actual performance increase you will experience. Too many variables to give a correct answer.
    – Moab
    Jan 2, 2011 at 19:37
  • 1
    @Moab: I think he said software RAID.
    – oKtosiTe
    Jan 2, 2011 at 19:52
  • That he did. he also said Raid 1, mirror will have absolutely no increase in speed, I think he has it confused with Raid 0
    – Moab
    Jan 2, 2011 at 20:12
  • I have hardware raid 1, it only reads from one drive, is it different for software raid?
    – Moab
    Jan 2, 2011 at 20:22
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    Raid1 can potentially improve READ speeds as each disk is read from in turn in much the same way as a striped array, remember, at this point the same data already exists on both disks. Writing data takes longer than normal as it has to duplicate the effort by writing the same data to both disks. The question refers to reading data. Since he only has one drive, he will not see any improvement at all.
    – Tog
    Jan 2, 2011 at 20:42

3 Answers 3


I think this blog answers it best. It shows actual speed tests for raid 0 and raid 1 between a single disk, windows software raid, hardware raid, and fake raid.


UPDATE: A more recent forum had a post from someone who tested Windows software RAID showing that the read speed was much faster, but the write speed was slower. If that is true then Windows software RAID is utilizing both disks independently. I have not verified these results myself. See the posting by ColgateJr near the bottom:


  • How does ColgateJr's test show an almost 100% increase in the sequential read for the Win7 RAID-1 setup vs individual disk, while KMWoley's test showed a negligible increase? ColgateJr's sequential write test also showed a 5% decrease in the sequential write, while KMWoley's test showed a 20% decrease. May 1, 2016 at 7:10
  • 2
    In theory one should be able to get up to a 100% increase in speed with RAID 1 reads. After all, you have two drives with the ability to read data independently from each one. But unless the software takes advantage of that ability, that's another question entirely. Perhaps Microsoft improved the RAID 1 ability in a service pack or update. I have not confirmed this.
    – Brain2000
    May 2, 2016 at 1:17

Just tested, 2-120GB SSD on windows 10.

RAID 0 increased both read and write dramatically (non-raid read was 450MB/s, raid-0 read was 820MB/s). Raid 1, write speed is the same, read speed increased by almost half (non-raid read was 450MB/s, raid-1 read was 631MB/s).

Side Note: I know were're talking about raid-1, but for someone who's speed hungry and want raid-0, just remember that if something slightly goes wrong with one of the drives, your system is done (crashes). Consider a raid-5 setup if you want both speed and redundancy.

  • raid 5 has incredibly show write. it's only good for reading speed.
    – Fractale
    Aug 7, 2019 at 5:56

Yes, theoretically it will increase the speed by n, because all n drives can access the same file at the same time. If you have 10 painters painting a room, theoretically, the work will go 10x faster than with one painter.

In reality, however, these 10 painters don't know how to work together. There's a ton of painting over and their styles don't match etc. Same with RAID1. Few operating systems have drivers that can utilize the benefits of RAID1 (I believe BSD may be the only remotely major one).

Conclusion: No, the software hasn't caught up yet. If you want speed and protection, you're better off buying one better drive than getting two crap drives, and perhaps investing in MozyHome.

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