I built a small 4-node all-flash VSAN for a specific use at my company. We didn’t need high performance, but we wanted the space efficiencies of dedupe/compression plus erasure encoding (in our R5).
Note that FTT=1, I could have tested FTT=2 for R1 but not for R5 so I didn’t bother.
4xDL380 Gen9 servers with 512 GB RAM connected via 10GB running ESXi 6.0u2 Patch 4
2xDiskgroups of 800gb cache SSD and 2×3.2TB SSD capacity
Overall, 40+ TB available prior to FTT and efficiencies
8 VMs 70 read, 100% rand, threads, 10 disks of 28GB, no warmup, ran for one hour. Most tests only 7/8 vms finished
*These tests had 8VMs finish, multiplied by 7/8 to scale the results
|Compression/Dedupe||No Compression/No Dedupe|
|R5 w/compress||R1 w/compress||R5||R1||R1 Hybrid|
My testing was a bit backwards, I started with R5 and compression and worked my way backwards. I should have started with R1 and no compression first and then layered on the other settings. Also, I had to turn compression/deduplication off which
From my testing, R1 with no compression/no dedupe was the fastest with 97721 IOPS, but I wasn’t looking for pure speed. I wanted to know what the performance penalty would be as we tried to save space. Looking at R1 compressed vs R1 non-compressed, R1 compressed is 58.91% of the IOPS of non-compressed, but compression can yield from 1.5x and up space savings
Comparing R5 and R1 uncompressed, 34764 vs 97721 IOPS or 33.58% of the R1 uncompressed. Savings would be around 1.33x (ratio is around 75%)
R5 compressed vs R5 was weird, it was almost the exactly the same though IOPs. Savings would be maybe 1.5x conservatively (ratio is around 67%)
R5 compressed vs R1 compressed was 60.39% of IOPS. Savings would be 1.33x convervatively (ratio is around 75%)
R5 compressed vs R1 was 35.57% which is the biggest difference, but the space used ratio is around 50%
R1 compressed vs R5 uncompressed is 165.58%, space used is ratio is about 88%
So what should you go with? Of course it depends.
Max storage: R5 with compression
Max performance: R1 no compression
Best mix of storage savings and performance: R1 with compression