Other Cool ZFS Features

There are many items that we have not touched on in this article, and those are worthy of mentioning at this time simply because they are enterprise features that are available with OpenSolaris and with Nexenta.  These are features that the Promise M610i cannot compete with in any way.

Block Level Deduplication - ZFS can employ block level deduplication, which is to say it can detect identical blocks, and simply keep one copy of the data.  This can significantly reduce storage costs, and possibly improve performance when the circumstances allow.  One group that recently deployed a Nexenta instance had originally configured the system for 2TB of storage.  They were using 1.4TB at the time and wanted to have room to grow.  By enabling deduplication they were able to shrink the actual used space on the drives to just under 800GB.  This also has implications when randomly accessing data.  If you have multiple copies of the same data spread out all over a hard drive, it has to seek to find that data.  If it's actually only stored in one place, you can potentially reduce the number of seeks that your drives have to do to retrieve the data.

Compression - ZFS also offers native compression similar to gzip compression.  This allows you to save space at the expense of CPU and memory usage.  For a system that is simply used for archiving data, this could be a great money and space saver.  For a system that is being actively used as a database server, compression may not be the best idea.

Snapshot Shipping - OpenSolaris and Nexenta also offer snapshot shipping.  This allows you to snapshot the entire storage array and back it up via SSH to a remote server.  Once you ship the initial snapshot, only incremental data changes are shipped, so you can conserve bandwidth while still replicating your data to a remote location.  Keep in mind that this is not a block level replication, but a point in time snapshot, so as soon as the snapshot is taken, any new data is not shipped to the remote system.

ZFS Features Nexenta
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  • mbreitba - Tuesday, October 5, 2010 - link

    Thanks for the comment on the ZIL.

    As far as using the X25-E's as ZIL devices - when we built the box initially, the X25-E's were the best choice at the time. Future builds will probably include a capacitor-backed SSD.
  • James5mith - Tuesday, October 5, 2010 - link

    For what it's worth, we are currently using roughly 16 of the Supermicro 846-E1 chassis in our storage solutions.

    Drive numbering is from bottom to top, left to right. Don't know if this helps or not.

    5 11 17 23
    4 10 16 22
    3 9 15 21
    2 8 14 20
    1 7 13 19
    0 6 12 18
  • badhack - Tuesday, October 5, 2010 - link

    I would be curious to know how the performance compares to traditional fs caching on Linux w/ ext3 or ext4 with same amount of memory and a few SSD drives.
  • Maveric007 - Tuesday, October 5, 2010 - link

    There are a few options within Linux that would be pretty interesting to see. FS caching and the different schedulers that are available within Linux. Also I would throw out ext3 and replace that with ext4 and xfs. Redhat is now supporting xfs and there are just tons of tunables for xfs compared to the other file systems.
  • badnews - Tuesday, October 5, 2010 - link

    Thanks Matt, I've been following the build over at your blog and this is an excellent article to tie it all together. I hope you follow up with your "things we'd do differently" in future articles. I would also love to see some more benchmarking against more alternatives, e.g. Open-E, or even an off-the-shelf EqualLogic.

    Keep up the good work :)
  • Fallen Kell - Tuesday, October 5, 2010 - link

    Well, I know at least for Solaris 10.... I would suspect that OpenSolaris has it as well by now, since it has been out for at least 4 years that I know of...

  • mbreitba - Tuesday, October 5, 2010 - link

    You can install the ZFS Web GUI from the Solaris toolkit, but it isn't bundled into OpenSolaris. It is binary compatible, but it doesn't give any good options for iSCSI setup, as it only supported the old iSCSI target rather than the new COMSTAR target.
  • sfc - Tuesday, October 5, 2010 - link

    How can you spend a page talking about how you aren't really worried about the future of Opensolaris, and then have half a paragraph mentioning "oh, btw, it's cancelled"? The project is clearly dead. They stopped releasing source almost a month ago. Oracle has made absolutely no guarantees about when or how source would be released in the future. For all we know, they could release only portions of Solaris Express, and do it months to years after the binaries drop.


    I love ZFS/Opensolaris, I use it at home, but Opensolaris is dead.
  • Mattbreitbach - Tuesday, October 5, 2010 - link

    OpenSolaris is indeed dead as far as development goes, but it's still viable if you want to use the last build released which is what all of our performance figures are based on. I will be writing some companion articles to this one talking about not only the death of OpenSolaris, but it's alternative, OpenIndiana, and the Promise M610i used as a comparison in this article.
  • andersenep - Tuesday, October 5, 2010 - link

    The OpenSolaris project may be dead but ZFS and all the CDDL licensed code is still out there. Illumos, OpenIndiana and a few other distros are still out there and available. Oracle has stated they will continue to release source code after Solaris releases and will also provide binary preview releases in the form of Solaris Express. To say Solaris and ZFS are dead is pretty premature.

    Whatever happens, the existing code is out there. To call it dead is a bit premature. Sure the project that had the name 'OpenSolaris' has been canceled, but everything that made it up (minus a small few closed bits that have already been replaced) lives on.

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