Tony Bar wrote:
'wafl awa' can help you determine the impact adding cache of either kind will have on writes/reads and how much optimally you would need. It is important to run it at a peak time to see what the recommendations are, as running it during a relatively low activity period won't give much useful information.
The best is really to let it run for several days, preferrably so that it fills up its DB of samples (1000 max, each is 600 s by default). Once it's done that, you're at stable state so to speak and you can trust what it says much more
Here's a sample output just to show you from one of our hard working NFS/CIFS Filers (no Block Storage traffic at all), it's a 8060c. Note that this system already has FlashPool (quite a lot too) on the only Aggr in each head. AWA will do its work anyway, suggesting if you should add more SSDs (provided you have the dough ;-) ) or if you've spent too much previously. N.B. AWA assumes the default policy everywhere: random_read-random_write
### FP AWA Stats ###
Host sekinaXXX Memory 61044 MB ONTAP Version NetApp Release 8.2.3P2D10 7-Mode: Thu Apr 9 22:11:11 PDT 2015 AWA Version 1 Layout Version 1 CM Version 1
Memory Allocation Memory Used 69848408 Malloc Count 16692 Mfree Count 29
Basic Information
Aggregate aggr0 Current-time Tue Jul 7 16:31:16 CEST 2015 Start-time Tue Jun 30 17:51:58 CEST 2015 Total runtime (sec) 599965 Interval length (sec) 600 Total intervals 1000 In-core Intervals 1024
Summary of the past 1000 intervals max Read Throughput 260.129 MB/s Write Throughput 172.245 MB/s Cacheable Read (%) 50 % Cacheable Write (%) 23 % Max Projected Cache Size 1251 GiB Projected Read Offload 68 % Projected Write Offload 22 %
Summary Cache Hit Rate vs. Cache Size
Size 20% 40% 60% 80% 100% Read Hit 61 62 63 67 68 Write Hit 19 19 21 21 22
The entire results and output of Automated Workload Analyzer (AWA) are estimates. The format, syntax, CLI, results and output of AWA may change in future Data ONTAP releases. AWA reports the projected cache size in capacity. It does not make recommendations regarding the number of data SSDs required. Please follow the guidelines for configuring and deploying Flash Pool; that are provided in tools and collateral documents. These include verifying the platform cache size maximums and minimum number and maximum number of data SSDs.