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3 Zinc

Re: Ask the Expert: Performance Calculations on Clariion/VNX

#EMCATE What makes the 14+2 RAID6 more efficient than the older 6+2 RAID6 for NL-SAS?

A good question from victor over on Twitter...

So for starters, the bigger the RG is, the more data disks you'll have compared to parity disks. In the new situation you'll have the nett capacity of 14 drives to allocate to servers. In the older 6+2 groups you would have to make two groups and still only end up with the capacity of 12 disks. Using 4 parity disks instead of a total of 2. This is just the financial aspect...

Performance wise, a bigger RAID group (obviously ) contains more drives, which will yield you more performance. However, watch out for the downside of this: rebuild times will be longer with larger RAID groups. Or, if you're rebuilding on ASAP rate, the impact on your storage (bus, disks, SP for parity calculations) will be larger.

If you want the performance and low rebuild impact, keep the RG's small and use striped metaLUNs to get you the amount of disks (=IOPs) you need. But you'll pay for it with $$

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6 Indium

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Better performance in the 14+2 compared to 6+2? If you look at it per GB the larger group performs a little less good!

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3 Zinc

Re: Ask the Expert: Performance Calculations on Clariion/VNX

can you explain the RAID10 write penalty. How it is 2 ? I hope atlease 1 read and 2 write is required (as mirrored) #EMCATE -7:23 PM Aug 23rd, 2012

For RAID10 or RAID1 writing, no readback is performed. If you change a block, it's written to the primary disk and the secondary disk: 2 write I/O's in total.

This is different from RAID5 where you need to read the old block, the parity (that's 2 reads), then write the new block and the new parity (that's 2 writes).

RAID6 builds on RAID5: you read the old block and the old parity blocks (dual parity), so 3 reads in total. And then you write it all back: data + parity blocks. 3+3=6!

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3 Silver

Re: Ask the Expert: Performance Calculations on Clariion/VNX

As discussed on twitter I've been using this DIY heatmap to visualize the CLARiiON performance on one view: http://www.penguinpunk.net/blog/emc-diy-heatmaps/

Check out the sample output file: http://www.penguinpunk.net/blog/wp-content/uploads/2011/12/heatmap.html

@henriwithani

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3 Zinc

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Want to find information about Navisphere/Unisphere Analyzer & to determine if U have performance issues? Refer KB Article:emc218359 #EMCATE -8:50 PM Aug 23rd, 2012

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3 Zinc

Re: Ask the Expert: Performance Calculations on Clariion/VNX

It's a wrap. The conversation continues on http://t.co/uYvJf5CQ Thanks to all participants #EMCATE -9:02 PM Aug 23rd, 2012

Seriously, thanks to all who participated in this tweetchat. I t was fun and informative. We plan to do a lot more of these #EMCATE -9:03 PM Aug 23rd, 2012

Thanks everyone, we had some great fun and good questions!

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6 Indium

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Absolutely! Let's do this again some time.

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3 Silver

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Other good series of post about perf analysis

http://storagesavvy.com/2011/03/30/performance-analysis-for-clariion-and-vnx-part-1/

@henriwithani

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6 Indium

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Thanks! This is good stuff!!!

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3 Argentum

Re: Ask the Expert: Performance Calculations on Clariion/VNX

Could you share some experience (best practice) on LUN layout design for OLTP & OLAP application?

thank you!

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