Hey,

We recently upgraded from MMAP to WT. For the same data amount (~500GB), on an AWS EBS volume which is "cold" (restored from a snapshot) - size 2TB -
MMAP took ~5 minutes to start
WT takes 50 minutes, log mentioning this:

Taking 1005 samples and assuming that each section of oplog contains approximately 5672862 records totaling to 1073741955 bytes

It apparently scans the oplog (we've set its size to 100GB) - and we see the iowait on 100%. But still, 50 minutes is a lot...

Anything we can do to speed things up?