Hi there, It is well-established that a wrong partition offset can have bad consequences. Say, your SSD disk operates with blocks of 4096 bytes and your OS has allocation units of 4096 bytes too (within the partition), BUT the partition itself begins at an offset which is not a multiplier of 4096. In this case, with each minimal writing operation, the OS would cause actual writing to 2 blocks instead of 1! Which leads to slower operation and extra wear. The built-in Disk Utility already aligns partitions by 4096 bytes by default. HOWEVER, some sources also say that for optimal performance, the partitions has to start at multipliers of 512KB, or even larger, depending on the erasing block size of the SSD and the number of its channels. In order to check where your partitions start, download an opensource utility GPTfdisk http://sourceforge.net/projects/gptfdisk/. Install it, then open a new terminal window and run "sudo gdisk /dev/disk0". Click "p" to list the partitions table. In my case (created by Disk Utitlity) it is: Number Start (sector) End (sector) Size Code Name 1 40 409639 200.0 MiB EF00 EFI System Partition 2 409640 430097143 204.9 GiB AF00 one So the main partition starts at sector 409640. Given that sector size is 512 bytes, the partition is aligned to exactly 4096 bytes. Now, the question is, is this good enough? Don't we need more, like suggested at http://www.ocztechnologyforum.com/f...you-need-to-know-in-easy-to-understand-format. ? (My disk is an OWC Mercury 240GB, though.) It would be especially helpful to hear from people with Apple factory-provided SSDs about how their partitions are aligned.