I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb RAM.
My test directory has ~ 3 million entries, and I loaded it into mdb using
slapadd which took over 2 days (by comparison, the same load into bdb takes 2-3 hours).
This is not normal. With slapadd -q MDB is faster than BDB assuming you're using a decent filesystem and sensible mount options. JFS, EXT2, do better than other filesystems in my tests. Very recent EXT4 may be better than EXT3 as well.
The filesystem is xfs, mounted as a drbd device (although at the moment the other half of the drbd pair is not configured, so it doesn't have to wait for synchronous writes across the network)
Sounds like you're not using slapadd -q. Either that, or your filesystem cache
Oh ****! You're quite right, I managed to lose the -q from the slapadd command when copy/pasting from a script. I'll try running it again with -q.
Do you have an ETA for improvements to mdb write performance?
Chris