ZFS:Hybrid Storage Pools

There has been a few announcements recently (and more to come) and here’s one that can really be a game changer and enabler for future tech advances:

Hybrid Storage Pools (HSP) are a new innovation designed to provide superior storage through the integration of flash with disk and DRAM. Sun and Intel have teamed up to combine their technologies of ZFS and high performance, flash-based solid state drives (SSDs) to offer enterprises cutting-edge HSP innovation that can reduce the risk, cost, complexity, and deployment time of multitiered storage environments.

Sun’s ZFS

Sun’s ZFS file system transparently manages data placement, holding copies of frequently used data in fast SSDs while less-frequently used data is stored in slower, less expensive mechanical disks. The application data set can be completely isolated from slower mechanical disk drives, unlocking new levels of performance and higher ROI. This ‘Hybrid Storage Pool’ approach provides the benefits of high performance SSDs while still saving money with low cost high capacity disk drives.

Solaris ZFS can easily be combined with Intel’s SSDs by simply adding Intel Enterprise SSDs into the server’s disk bays. ZFS is designed to dynamically recognize and add new drives, so SSDs can be configured as a cache disk without dismounting a file system that is in use. Once this is done, ZFS automatically optimizes the file system to use the SSDs as high-speed disks that improve read and write throughput for frequently accessed data, and safely cache data that will ultimately be written out to mechanical disk drives.

Intel’s SSDs

Intel’s SSDs provide 100x I/O performance improvement over mechanical disk drives with twice the reliability:

  • One Intel Extreme SATA SSD (X25-E) can provide the same IOPS as up to 50 high-RPM hard disk drives (HDDs) — handling the same server workload in less space, with no cooling requirements and lower power consumption.
  • Intel High-Performance SATA SSDs deliver higher IOPS and throughput performance than other SSDs while drastically outperforming traditional hard disk drives. Intel SATA SSDs feature the latest-generation native SATA interface with an advanced architecture employing 10 parallel NAND Flash channels equipped the latest generation (50nm) of NAND Flash memory. With powerful Native Command Queuing to enable up to 32 concurrent operations, Intel SATA SSDs deliver the performance needed for multicore, multi-socket servers while minimizing acquisition and operating costs.
  • Intel High-Performance SATA SSDs feature sophisticated “wear leveling” algorithms that maximizes SSD lifespan, evening out write activity to avoid flash memory hot spot failures. These Intel drives also feature low write amplification and a unique wearleveling design for higher reliability, meaning Intel drives not only perform better, they last longer. The result translates to a tangible reduction in your TCO and dramatic improvements to system performance

Benefits of HSP

Architectures based on HSP can consume 1/5 the power and 1/3 the cost of standard monolithic storage pools while providing maximum performance.

For example, if an application environment with a 350 GB working set needs 30,000 IOPS to meet service level agreements, 100 15K RPM HDDs would be needed. If the drives are 300GB, consume 17.5 watts, and cost $750 each, this traditional environment provides the IOPS needed, has 30TB capacity, costs $75,000 to buy, and consumes 1.75 kWh of electricity.

Using a Hybrid Storage Pool, six 64 GB SSDs (at $1,000 each) provide the 30,000 IOPS required, and hold the 350GB working set. Lower cost, high-capacity drives can be used to store the rest of the data; 30 1TB 7200 RPM drives, at $689 each ($20,670) and consuming 13 watts, provide cost-effective HDD storage. The savings are dramatic:

  • Purchase cost is $26,670, a 64-percent savings
  • Electricity consumed is 0.392 kWh, a 77-percent savings

Link to docs:

Solaris ZFS Enables Hybrid Storage Pools – Shatters Economic and Performance Barriers

UPDATE: Brendon from the Fishwork team has posted some speed and performance notes here

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2 responses

  1. We have a large HTTP/FTP file archive (mirror.switch.ch) based on a T5220 server with Sun StorageTek 2530 SAS/SAS disk arrays. This performs very nicely, we have served >3.5Gb/s from this single machine during the peaks of some release events (e.g. Ubuntu). We’re considering to move to cheaper/larger/less power-hungry SATA disks with some SSD cache.
    Because this box is so heavily dominated by read access, I think "enterprise-grade" SSD would be a waste of money. Can we use "consumer-grade" SSDs as well with ZFS? Write performance would suck, but I wouldn’t care because, as I said, we’re heavily biased to reads.

  2. Hi Simon, If you’re talking about multi-level cell (MLC) flash memory vs single-level cell (SLC) flash memory, there still seems to be a perception that MLC isn’t as good or reliable but it’s cheaper.
    If you go for MLC route, ZFS is your friend (assuming you have either Solaris 10 U6 or OpenSolaris 2009.06) then add the SSDs for L2ARC. See Brendan’s excellent intro here: http://blogs.sun.com/brendan/entry/test
    If an SSD (L2ARC device) fails, the system continues to operate returning read requests that would have been cached by that device directly from disk.
    It might also be worth checking out the OpenStorage as a longer term solution: http://www.sun.com/storage/openstorage
    here are some other useful links:
    http://blogs.sun.com/ds/entry/more_zfs_goodness_the_opensolaris
    http://anandtech.com/storage/showdoc.aspx?i=3631
    http://breden.org.uk/2009/08/29/home-fileserver-mirrored-ssd-zfs-root-boot/

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