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Just trying to give back to the technical community that has helped me along the way.  Please write me if you have any questions I will always try to help you out.

  1. John
    September 6, 2011 at 12:12 pm

    I would like to know when and where do we use Lun clone and Flex clone.

    Please help .

    Thanks
    John

    • October 3, 2011 at 1:01 pm

      John I just noticed you left a comment a while back, sorry for the late reply. Please give me more detail of your problem or concern and I will try to help you out. Your question for which one you should use will be based on what you’re trying to accomplish. 98% of the time though I will recommend Flex Clone over LUN clone but again I don’t have all the info to tell you either way yet.

  2. sujith
    October 3, 2011 at 11:32 pm

    thank you for the reply ,
    Actually i wanted to know the difference. I read the article and understood how both works – but can you please share an example scenario where one decides whether to go for ‘Flex Clone’ or ‘Lun Clone’ .

    Thanks ,
    John

    • October 6, 2011 at 2:15 pm

      It’s not like if you’re using Exchange then you use Flex Clones and if you’re using a SQL database then you should use LUN Clones…. a clone is a clone but how you handle the clone (and snapshots) is the differences. Flex Clones does it better, in my opinion. LUN Clones creates a clone based on a snapshot, but the clone is created within the volume, and only of a particular LUN. This is infact a very similar concept to that of the new Single File FlexClone available in 7.3. Based on a given snapshot, you will have a new LUN created within the same volume as the parent LUN. This will use no storage, and is great for running verifications, or possibly testing or even reporting.

      The problem arises due to the nature of snapshots and the LUN clone. A snapshot takes a copy of the file pointer tables of an entire volume. A LUN clone will create a thin-provisioned clone of the parent LUN within the same volume. So despite using no actual storage, the LUN clone will get snapshotted by any new snapshots taken after the LUN. This is where the problems start. If we now delete the LUN clone, the clone will still exist within a snapshot, so the LUN will still be locked. If you aren’t quick and noticing this issue, you may have a lot of snapshots that are all locking this LUN clone.

      So how does FlexClone offer you protection? Well, it creates and clone of the entire FlexVol, and as snapshots are based on the volume, any subsequent snapshots will not contain any information regarding this clone. The clone is based on a single snapshot, so potentially if a verification fails, or you forget to destroy a FlexClone, you can get yourself into a situation where scheduled backups are unable to remove this old snapshot, but this is simple to fix. Either destroy the FlexClone or split it off, the snapshot is then released, and you are back to normal. A lot smoother than LUN Clones!

      Unfortunately I still see LUN clones affecting production environments quite often. My recommendation is always to try include FlexClone, or at the very least be very pro-active with monitoring of your backups. FlexClone offers a lot of other benefits besides this, so I feel it is a worthwhile investment. Hope that helps… it’s the best I can explain it.

  3. sujith john
    October 6, 2011 at 11:32 pm

    Thanks alot , that was very clear.

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