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casualcoder
Asked: 2009-12-06 09:07:14 +0800 CST

Using SSD as disk cache

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Is there software for Linux to use an SSD as disk cache? I believe that Sun does something like this with ZFS, though not sure. A quick search provides nothing suitable. The goal would be to put frequently requested files on the SSD on-the-fly. Since the SSD has more capacity than RAM for less money and better performance than hard disk, this should provide an efficient performance boost.

linux

4 Answers

  1. Best Answer

    Facebook recently released a module for the Linux kernel called 'FlashCache' which can do exactly this:

    http://github.com/facebook/flashcache

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  2. Have you looked into Bcache? http://bcache.evilpiepirate.org/

    I realize this is an old topic, hope this helps anyone else who might have arrived here like me with an ssd cache question.

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  3. With SUN's ZFS, SSDs can be used as L2ARC cache [1], using the zpool add cache command:

    cache

    A device used to cache storage pool data. A cache device cannot be cannot be configured as a mirror or raidz group. For more information, see the “Cache Devices” section.

    I know nothing similar with Linux filesystems. I don't know if it would be suitable, but one thing you may try would be to add swap on SSD and tune the `swapiness' Linux kernel parameter (sysctl vm.swapiness)

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  4. I don't think there's a simple way to do this on Linux yet. ZFS is available as a userspace filesystem, but it's not very good. Some ZFS clones are on their way, but as far as I know nothing is ready for production.

    Perhaps you could consider a BSD with ZFS?

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