Ævar Arnfjörð Bjarmason wrote:
Partitioning the servers in an optimal manner for us is something I'm not as comfortable with. I could figure it out if necessary, but Saper is probably better capable of that. One thing I do know is that the database logs should be on separate partition from the database itself, and both kept separate from the OS.
I can't remember what sort of RAID setup we have. Depending on the RAID how we partition might not matter at all.
It's RAID 1+0 that means:
16 drives 140009MB each every pair of drives is a mirror everything is concatenated to be a single, large volume, 140009MB x 8 = 1120072 MB ~ 1119200 MB is the logical volume we have (in fake megabytes)
Without having tried it I wouldn't think that putting logging on a separate disk doesn't help that much. Logging doesn't take up so much I/O. However keeping the database and its indexes on separate disks evidently helps a lot. See recent discussions on osm-dev/talk about database setup.
We might move OS and software important stuff to a separate mirror (2 drives - but we waste 280GB for that then) and consider splitting the rest for the DB purposes, keeping individual mirrors for safety and concatenating as required for the database.