On Sun, Mar 15, 2015 at 9:21 AM, Felix Miata
I've yet to find a real world evaluation of the performance penalty imposed by not aligning to 4k.
Umm? There is no good reason to not align, so why does this matter? And for two, there's piles of evaluation of this on linux-raid@ and it's all over the map because the penalty depends highly on workload, and the firmware revision. Some drives are just really slow with the internal read-modify-write, and others have optimized this so it's a minimal effect. The only way to evaluate this is to test it, but why bother? Just align properly. All the tools used these days do this correctly, parted, fdisk, gdisk, and so on.
The original has lots of 255/63 partitions. Most of my filesystems use 1k blocks.
I seriously doubt that. And I don't think it's even possible because the normal kernel pagesize on x86 is 4KiB since forever, and the file system block size has to be a multiple of that which makes 4KiB the minimum fs block size on x86. For tools at least 5 years old, ext4, XFS, and Btrfs all default to 4KiB block sizes. Btrfs still uses a 4KiB block size but now uses a 16KiB node/leaf size by default for storing metadata and inline data.
I usually have only one large blocksize partition use for truly large files, like CD & dvd isos. The backup system includes/assumes 255/63 too.
Are you referring to CHS addressing? This hasn't been used in Linux with any drive since probably 15 years or more.
I don't want to conform to 4k before I know what the nuts & bolts cost of non-conformance is. Maybe I'd be happiest by ignoring alignment in test systems, conforming only in 24/7 systems, if even then.
You are needlessly making a big deal over a long ago solved problem. It occasionally remains an issue with dual boot installs with Windows XP and newish drives, because XP's partitioner starts the first partition at LBA 63, which is not aligned. It sometimes comes up with older enterprise linux that for some reason dragged their feet applying patches to start the 1st sector at LBA 2048. But I'd be surprised if you're using any version of openSUSE released in the past ~8 years that does this incorrectly. But all you have to do is look at the start LBA for each partition. Is it divisible by 8 (or 2048 if you want 1MiB alignment - it's easier)? If yes, you're done. If no, start over. -- Chris Murphy -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org