Aligning partitions to start at real physical sector of ssds / stripped raids / 4kB drives is a 'good thing to do', but I've run into a problems when trying to do it for a truecrypt partition that will contain ext3 on it. Or so it seems.
When drive in question is partitioned properly and formatted with ext3 I get very reasonable write speeds around 70-80MB/s, but when I put truecrypt and ext3 on the top of it write performance becomes very unstable and goes between 1-25MB/s with very high io-wait. On the same server I don't have any performance issues with ext3 on the top of truecrypt on regular 512B-sector 500GB sata disks. So my best guess is that iowaits are caused by misalignment but I cannot really find reliable information on how to calculate optimal partition beginning. I've tried to start it at 128 logical sector, I've also tried 8132 sector as suggested here but both gave me very bad and unstable performance.
Do you have any experience with similar setup? Thanks!
ps - quote from truecrypt forum: When I encrypted the partition with Truecrypt, I only got 8Mbyte/sec because it does not place the start of the volume at sector 8192, but instead it places the volume at the end of the track which 8192 belongs to. I have 63 sectors per track, so sector 8192 is the second sector of the 130th track. Truecrypt started its volume at the end of this track (sector number 8252), which is 60 sectors too far. So the solution was to move the partition back by 60 sectors, so the partition started at 8132 instead of 8192. This caused the first sector of the Truecrypt volume to be located at the magic sector 8192.