Why mongodb performance doesn't improve when i enable piops

[Winston Yang]

Basically we are going to setup mongodb in aws, we tried to setup two databases for testing:

1. no piops, ebs-optimized off, with standard ebs

2. piops 4000, (500GB ebs), ebs-optimzed on.

But when we try to run mongoperf, with the same setting, echo "{nThreads:10,fileSizeMB:1000,w:true}" | mongoperf

in the first instance (no piops), we can get about 1000+ ops/second (write)

1253 ops/sec 4 MB/sec

1294 ops/sec 5 MB/sec

I thought the piops instance should be better.. but actually the result is worse than standard ebs. We can only reach 500 ops/second

530 ops/sec 2 MB/sec

266 ops/sec 1 MB/sec

296 ops/sec 1 MB/sec

312 ops/sec 1 MB/sec

How can i check?  seems we make something wrong here or miss something?

[Winston Yang]

even when we try to use the 10gen AMI in amazon,

https://aws.amazon.com/marketplace/seller-profile/ref=sp_mpg_product_vendor?ie=UTF8&id=c9032c7b-70dd-459f-834f-c1e23cf3d092

ami with 1000 piops, vs standard ebs

this is the standard ebs:

1244 ops/sec 4 MB/sec

1277 ops/sec 4 MB/sec

1239 ops/sec 4 MB/sec

1097 ops/sec 4 MB/sec

1278 ops/sec 4 MB/sec

1230 ops/sec 4 MB/sec

the ami with 1000 piops in AMI market

678 ops/sec 2 MB/sec

766 ops/sec 2 MB/sec

625 ops/sec 2 MB/sec

736 ops/sec 2 MB/sec

664 ops/sec 2 MB/sec

still half of standard one?