Quoting Robert L Mathews lists@tigertech.com:
On 3/15/16 10:13 AM, Sven Hartge wrote:
I don't have a script, but I can provide some numbers. I did a test with a server for about 10.000 users and 2TB worth of mail, converting from Maildir++ to mdbox with zlib (level = 6) and had a final size of 1TB, so 2:1 reduction.
These numbers roughly match my results. About 6 TB of mail compresses down to about 3 TB.
Also keep in mind that even if it does increase CPU usage, it reduces disk usage. This is probably an excellent tradeoff for most people, since most servers are limited by disk throughput/latency more than CPU power.
Just thought I'd add, because it frustrated me and it's an amusing anecdote to this - The new 4k ashift doubled my disk usage of Maildir++ mail.
So logically, if you're migrating from maildir++ to mdbox on 4k sector system, you may see a sizable decrease in disk usage without a compression change.
Rick