Align 2KiB is sector alignment (1MiB for standard 512 byte sectors).
"rustleg" wrote in message news:firstname.lastname@example.org...
Due to the recent post by Jeffrey Lee
I have been looking into SSD partition alignment recommendations. I'm
Various recommendations I have seen are
1. 4KiB alignment
2. You should only need to make sure that the start and end sectors of
partitions are multiples of the size of your erase block. The Erase Block
Size is largely vendor specific. (my SSD is Intel 320 120GB - not found the
erase block size)
3. General consensus is to start your first partition at 1,048,576 bytes, as
it is evenly divisible by 512, 4096, 131,072, and 524,288 bytes, covering
all sector, filesystem block, and erase block size possibilities.
4. (Linux) -remember that fdisk in Linux uses â€œheadsâ€ and â€œtracksâ€ to define
cylinders. If the cylinder boundary is not aligned with the â€œpageâ€ of an
SSD, then the SSD can easily undergo extra work during a read/modify/write
cycle. By default, Linux fdisk uses a default geometry of 255 heads, 63
sectors/track, and, still currently, 512-byte sectors. This results in
16,065, 512-byte sectors per cylinder (2,008.125, 4KB pages). This is
definitely not aligned on 4KB pages. So we need to adjust the geometry to
align the cylinder boundaries on 4KB pages so that any partitions are
aligned on page boundaries.
It is claimed that Windows 7 automatically starts a partition at the front
of a drive at the 2MB point (2048k) - if you set up the partition with BIBM
initially this presumably is not applicable (unless Windows leaves the first
I believe the recommendations are made to optimise writing pages and
erasing blocks (which are multiples of pages). Personally I don't see the
logic regarding erasing as the OS doesn't delete files based on blocks or
pages. So even if you aligned on a block the OS would still fragment the
content of blocks. Regarding writing pages I understand a page is usually
4KiB so ideally one would want the OS to write in aligned 4KiB chunks.
As Windows' NTFS partitions use 4096 byte clusters maybe alignment to 4KiB
I also use Linux and checking my Mint 11 root partition the block size is
So my take at the moment is I'd like to align at 4KiB. However BIBM seems
only to be able to align at 2KiB. Looking at TB's Knowledgbase article
"Understanding 4K Sector Drives and WD Advanced Formatting" it
You can use BootIt Bare Metal to align your new or existing partitions by
enabling its global Align at 2048 option. So am I to assume this option is
targeted at hard disks not SSDs?
In the IFW manual there's an option to align based on 2048
[b:n2yvmx3k]sectors[/b:n2yvmx3k] (not bytes) "Use 2048 Sector
Alignment â€“ Use this option to instruct Image for Linux to align restored
partitions based on 2048 sectors." However this doesn't seem to be
possible with BIBM options when creating a partition in the first place.
In TB support's reply to the above mentioned post it mentions using the 2KiB
alignment in BIBM. Is this sufficient?
Any help or information on the above would be very welcome.