Volker Armin Hemmann writes:
Am Sonntag, 26. August 2012, 13:41:09 schrieb Alex Schuster:
Frank Steinmetzger writes:
Unless the filesystem knows this and starts bigger files at those 512 k
boundaries (so really only one erase cycle is needed for files <=512 k),
isn't this fairly superfluous?
Yes, I think it is. When you search for SSD alignment, you read about
this alignment all the time, even on the German Wikipedia, and many
resources say that this can have a big impact on performance. But I
could not find a real explanation at all.
Besides that, it's not so easy to do the alignment, at least when using
LVM. I read that LVM adds 192K header information, so even if you align
the partition start to an erasable block size of 512K, the actual
content is not aligned. See [*] for information how to overcome this.
That is, if you believe the alignment to erasable blocks is important,
personally I do not know what to think now. It wouldn't hurt, so why not
apply it, but it seems like snake oil to me now.
Wonko
http://tytso.livejournal.com/2009/02/20/
because erasing is slow. You can not overwrite data on a ssd. you have to
erase first, then reprogramm. Also, erasing shortens lifetime.
Yes, I know that. But why exactly does it help to align a partition to
the erasable block size? I don't get it. Why isn't it sufficient to
align to the usual 4K block size, so that a block never spans over two
erasable blocks?
Wonko
