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ronst

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ronst

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October 10th, 2012 00:00

Recommended Checkpoint interval

Hello,

I hope you can help.

my customer has a requirement for their CIFS home directories, they want checkpoint every 10 minutes and 24h data retention, self-service file level recovery.
What checkpoint interval should I recommend ?

How do I calculate this ?

  • Rainer_EMC

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    Posted October 10th, 2012 02:00

    It is possible

    I would negotiate for a lower number though. For example 10 min for an hour and then hourly checkpoints

    6 x 24 = 144 – if you have more file systems then you need to consider the total amount of file system + checkpoints per system

    This also has an influence on the boot and failover time.

  • golnaz1

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    Posted August 13th, 2013 17:00

    andre.rossouw

    Can anyone answer this question please , this asked couple of times but I couldn't find any answer for it.

    Thank you

  • umichklewis

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    Posted August 14th, 2013 06:00

    I think Rainer provided an answer above.  One thing to consider - there is a limit to the total number of checkpoints per filesystem; 144 exceeds that limit.  Moreover, having more checkpoints per filesystem increases the time required to failover or reboot a datamover.  Rainer's recommendation - 10 minute checkpoints, saved for an hour + hourly checkpoints, saved for a day - is very reasonable.

    In our environment, I keep a checkpoint every four hours for a day, seven daily checkpoints for a week and four weekly checkpoints for a month.  This allowed users great flexibility and dropped our help desk calls for restores dramatically.

    Let us know if that helps!

    Karl

  • golnaz1

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    Posted August 14th, 2013 17:00

    Thanks @Karl,

    Your explanation is clear but I', still confused. I think the check point limit is 96. You calculated:

    6 (checkpoints per hour) * 24 (retention) = 144 which exceeds 96. Then you recalculated:

    The question asking about checkpoint interval and answers are:

    20

    30

    60

    45

    and 20 is the correct answer, how we get 20 ?@

  • umichklewis

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    Posted August 15th, 2013 08:00

    The limit to the total number of checkpoints per filesystem is 96.  What Rainer was illustrating was that 6 X 24 = 144 which is too many checkpoints.  He was illustrating that to the original poster, so that the poster could negotiate fewer checkpoints with his customers.

    The rest of your question, I don't understand - it looks like you're asking something from the VNX TA exam.

  • golnaz1

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    Posted August 15th, 2013 17:00

    Thank you Karl ,

    Yes it is . It is from E20-324 .I have posted couple of questions for this exam but I haven't got any response yet !

  • umichklewis

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    Posted August 16th, 2013 06:00

    Repost the question here and I'll have a look!

  • golnaz1

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    Posted August 17th, 2013 17:00

    Appreciate your help,

    A customer has a requirement for their CIFS home directories, they want checkpoint every 10 minutes and 24h data retention, self-service file level recovery.

    What checkpoint interval do you recommend ?

    20

    30

    60

    45

    I need some help in couple of questions and I couldn't find any answer for them, is there anyone we can refer to ask e20-324 related questions?

  • dynamox

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    Posted August 17th, 2013 17:00

    just because customer wants snapshot every 10 minutes and keep for 24 hours does not mean the system can accommodate that. That's 6 x 24 = 144 , obviously 144 is more than Celerra/VNX supports at the moment (max 96 snapshots per file system) so your next recommendation is 20 minute interval (3 x 24 = 72)

  • golnaz1

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    Posted August 17th, 2013 18:00

    Thanks dynamox for your perfect explanation.