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Sorry for the delay on this next post..  Between EMC World and my 9 month old, it’s been a battle for time…

Okay, so you have an EMC Unified storage system (Clariion, Celerra, or VNX) with FASTCache and you’re wondering how FASTCache is helping you.  Today I’m going to walk you through how to tease FASTCache performance data out of Analyzer.

I’m assuming you already have Analyzer launched and opened a NAR archive.  One thing to understand about Analyzer stats as they relate to FASTCache, is that stats are gathered at the LUN level for traditional RAID Group LUNs, but for Pool based LUNs, the stats are gathered at the pool level.  As a result graphing data for FASTCache differs for the two scenarios.

First we’ll take a look at the overall array performance.  Here we’ll see how much of the write workload is being handled by FASTCache.  In the SP Tab of Analyzer, select both SPs (be sure no LUNs or other objects are selected).  Select Write Throughput (IO/s), and then click the clipboard icon (with I’s and O’s).

Launch Microsoft Excel and paste into the sheet, and then perform the text-to-column change discussed in the previous post if necessary.

Next create a formula in the D column, adding the values for both SPs into a single total.  We’re not going to graph it quite yet though.

Back in Analyzer, deselect the two SPs, switch to the Storage Pool Tab, right-click on the array and choose Select All -> LUNs, then Select All -> Pools.

Click on a RAID Group LUN or Pool in the tree, it doesn’t matter which one, deselect Write Throughput (IO/s) and select FAST Cache Write Hits/s.  In a moment, you’ll end up with a graph like this.

Click the clipboard icon again to copy this data and paste it into a new sheet of the same workbook in Excel.  Insert a blank column between column A and B, then create a formula to add the values from column B through ZZ (ie: =SUM(C2:ZZ2).

Then copy that formula and paste into every row of column B.  This column will be our Total FAST Cache Write Hits for the whole array.  Finally, click the header for Column B to select it, then copy (CTRL-C).  Back to the first sheet — Paste the “Values” (123 Icon) into Column E.

Now that we have the Total Write IOPS and Total FAST Cache Write Hits in adjacent columns of the same worksheet, we can graph them together.  Select both columns (D and E in my example), click Insert, and choose 2D Area Chart.  You’ll get a nice little graph that looks something like the following.

Since it’s a 2D Area Chart, and not a stacked graph, the FASTCache Write IOPS are layered over the Total Write IOPS such that visually it shows the portion of total IOPS handled by FASTCache.  Follow this same process again for Read Throughput and FASTCache Read Hits.  Furthur manipulation in Excel will allow you to look at total IOPS (read and write) or drill down to individual Pools or RAID Group LUNs.

Another thing to note when looking at FASTCache stats…  FAST Cache Misses are IOPS that were not handled by FASTCache, but they may still have been handled by SP Cache.  So in order to get a feel for how many read IOs are actually hitting the disks, you’d actually want to subtract SP Read Cache Hits and Total FASTCache Read Hits (calculated similar to the above example) from SP Read Throughput.  This is similar for Write Cache Misses as well.

I hope this helps you better understand your FASTCache workload.  I’ll be working on FASTVP next, which is quite a bit more involved.

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