Aligning filesystems to an SSD’s erase block size

[nhasian]

I just purchased two Corsair P128 SSD for use with my Laptop and Desktop with Ubuntu Lucid Lynx 10.04. I understand for the drive to be set up properly I need three things:

 

Partition Offset ÷ NAND Page Size Aligned

Partition Offset ÷ NAND Erase Block Size Aligned

Partition Offset ÷ File Allocation Unit Size Aligned

 

What i don't understand is how to go about getting this done in linux. I plan on making a 10 gig partition for root and the remaining space /home. I can make a swap partition on my secondary HDD. I'm comfortable with using gparted but to my knowledge it does not allow for this level of detail when creating partitions. So i think i'm stuck with fdisk. I also have an unopened Windows7 sitting in my desk drawer. I wonder if I could just cheat and tell the windows7 installer to create two partitions for me then change them to ext4 in gparted...

[NfiniteZERO]

That's what I'd do. I wish I could tell you how to do it with Linux but I'm way rusty on the subject.

 

Creating the partition with Win7 or Vista will take care of this automatically.

[RAM GUY]

I am sorry but it would be best to contact the maker of the O.S. you plan on using, we cannot offer support for any open source software.

[nhasian]

I am sorry but it would be best to contact the maker of the O.S. you plan on using, we cannot offer support for any open source software.

 

maybe this will help:

 

By default, Ubuntu 10.04 LTS aligns partitions on disk to 1 MiB (1048576 bytes) boundaries. This ensures maximum performance on many modern disks, particularly solid state drives but also new "Advanced Format" disks with physical sectors larger than the traditional 512 bytes. Very few systems nowadays need the old alignment, used in the days of MS-DOS when it was useful for partitions to start at the beginning of a cylinder.

 

See the release notes for Ubuntu Lucid Lynx 10.04

[NfiniteZERO]

nhasian, that looks like what you need for the partition alignment as Win7/Vista align to the 1MiB boundary.

 

The next part would be deciding what filesystem you plan to use and what the default allocation size would be. I'd recommend 4k from my experience with my SSD on NTFS.

 

Most SSDs I've found use NAND that uses 4k pages and 512k erase blocks. Can't find anything more specific in regards to Corsair's NAND flash but I believe it's the same.

 

Best of luck and enjoy your SSD.

[nawk]

Most SSDs I've found use NAND that uses 4k pages and 512k erase blocks. Can't find anything more specific in regards to Corsair's NAND flash but I believe it's the same.Best of luck and enjoy your SSD.

 

With regards to the NAND page size, I'd think it is safe to assume 4K, OTOH not all SSDs have an erase block size of 512KiB (e.g. Intel X25-M's erase block size is not 512KiB).

 

I am currently thinking about picking up two 120GB Force Gt's and is reading benchmarks and reviews on it. I, along with many Corsair customers, hope to get some official response as to what the erase block size on the Corsair SSDs.

[RejZoR]

I'm a bit confused here. When i was checking my Windows XP system on netbook it said that allocation unit is 4K, meaning it's actually using the right alocation unit for SSD despite the fact it's WinXP. Or am i missing something here? I never really got this alignment thing with SSD's. They all brag how important it is but no one provides utility to align it easily for anyone.

They just all assume you use Windows 7 with SSD's. Which is just not true.