Selena’s Pg FS talk
- ext3 gives much faster random writes throughput than ext2.
- Maybe because the seek bundling is faster?
- But adding a disk to ext2 makes sequential writes much faster.
Only have 4 disks? What should you do?
- RAID 5 outperforms everything else for random writes.
Make your readahead buffer about 1MB.
- Conventional wisdom
“Raid 5 is the worst choice for a database.” Fast for dsequential
writes in our tests.
“Turning off atime is a big performance gain.” Not in our tests,
but 2-3% for free.
“Journaling FSes have worse performance than non-jounraling.”
Turning it off improves perfornance, but there are edges cases and
differenes we could not explain.
“Striping doubles performance.” Performance is better, but nowhere
Your reader-ahead buffer is not big enough. Make it 8MB.
“JFS was pretty awesome.”