back to article Will multi-tier flash arrays come to a data centre near you?

Multi-tier storage is a familiar concept in data centres and large server installations. In the old days, this was often a simple case of having a single-access bus type with different-speed disks, for example SCSI-based disk arrays with 15,000rpm disks in the “fast” set and 7,200rpm or 5,400rpm in the “slow” set. Commonly, …

  1. Rob Moss

    And when will we start to see desktop drives employing SLC, MLC and TLC in a single drive? Surely that's the logical extension of this? You don't need a huge SAN to have a clever controller.

    1. Anonymous Coward
      Anonymous Coward


      Samsung and Sandisk do this already. Maybe not all three but TLC drives with a SLC cache.

      I'm hearing in the channel that since a single SSD drive outperforms an array of 15krpm drives, HP et al. are about to stop sales of the 15krpm drives. Price-wise the enterprise SSD's are still damn expensive and the even some prosumer drives have great endurance these days.

  2. Anonymous Coward
    Anonymous Coward

    Find me a 6TB solid state drive

    I'm not sure there's a future for 15K spinning drives, or even 10K ones in a SAN.

    But I'm sure that until we can get SSD with the capacity and reliability of 4TB or soon to be 6TB spinning drives at a similar cost/GB, there's a future for the rusty stuff.

    Dell's Compellent has gone in this direction with SLC and MLC - using each for write-intensive and read-intensive data, which lowers the overall SSD cost by leevraging the strengths of each type. TLC isn't there yet on its wear rate and Dell still allows a spinning tier of big fat drives for resting data. I think it's an interesting design.

    There are some other designs on the market where drive combinations are working well, but I don't know of any others where SLC and MLC are being incorporated as 2 of a 3 tier model.

    TLC wear rates may improve, but much more likely is that the cost of MLC will drop, capacities will increase and the density and power/heat characteristics will start to make this a preferred option over a 3 drive type model. We're years off this, though, I should think.

    1. M. B.

      Re: Find me a 6TB solid state drive

      The Compellent flash stuff works really well, having owned a hybrid systems with flash and disk. I found I had to let the data settle when migrating to the array so as to not fill the SLC tier too quickly. Once the colder data has de-staged to lower tiers you just let all the new writes hit SLC and let the array sort out the placement as it cools. Typical flash array performance, sub-millisecond latency and ridiculous IOPS, plus some added efficiency through thin writes and de-staging to more cost-effective media.

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