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Background / Setup

  • I have a desktop that I built (Full Specs here if you need them for reference).
  • It currently utilizes 2x1TB drives (SATA 6.0 Gb/s) in a RAID1 configuration.
  • I use Intel RST to use a 64 GB SSD in front of the RAID1 as a cache.


  • I would like to update these to 3TB drives due to a great sale.


  • I'm worried about performance suffering. Given this setup with an SSD cache, would putting 2x3TB SATA 3.0 Gb/s drives in RAID 1 slow down the speed dramatically?
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up vote 4 down vote accepted

I have two 3TB drives in a RAID 1 on SATA 3gbs. So I did a benchmark for you with small transfers that would fit in the drives cache, as these are going to be the fastest transfers they can achieve, sustained transfer rates are much lower.

enter image description here

If you check the image even the small bursts only get up to 200MBs about 100 MBs short of the sata 3Gbs. You should notice no performance difference with spinning drives between SATA 2 and SATA 3. The volume D pictured above is a RAID 0 with 10k drives on 6Gbs link and they barely push over the 3Gbs mark. I wouldn't worry about performance with any consumer grade spinning disk between between the two SATA revisions. However, certain SSD's can greatly benefit from 6Gbs as single drive volumes can get very close to the SATA 3 limit of 6Gbs.

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