SSD Partition Alignment - offset?

Hi

I'm reading a lot on how disk partition alignment can improve SSD (and hard disk) performance. I'm curious what offset you SSD owner use on what brand /type. And, what are the factory partition alignments when you bought a notebook with a SSD?
You can check the partition alignment using diskpar.exe, diskpart.exe or MSINFO32.exe.

Big Thanks!

 

I have a WD Black Caviar 320

Partition Starting Offset 210,763,776 bytes

I cloned a new Dell drive over to it though.

 

I can't see how it would improve performance on a SSD.
Only a mechanical harddrive as it has a round mechanical platter with DATA, the beginning of a regular harddrive has the best performance in the beginning and gets slower at the end.

SSD has the same speed all over the disk as it isn't made of any mechanical parts what-so-ever! So, say what? Am i missing something out here?

 

Apperently, it does improve performance.

Check this thread:
http://www.ocztechnologyforum.com/forum/showthread.php?t=48309

or:

http://download.microsoft.com/downlo...T558_WH08.pptx

 

How i understand it, unlike mechanical drives, partitionning an SSD doesn't give you performance advantage. BUT, if you DO partition it, aligning the partitions is essential to prevent deterioration of performance.

 

There are huge differences with the way the drives work that means aligning a partition can increase the responsiveness of SSD based drives. OCZ has a good write-up about it and it has been shown to reduce the "hanging" that the cheaper SSD drives show with random writes.

HDD's use sector sizes of 512bytes, usually 8 of these sectors make up a cluster of 4K. It is not to bad if the partition is slightly out as it will only mean an additional 512bytes of data will be read or written for each cluster read.

SSD drives have a sector size of 4K and one whole sector is used to make up the usual windows cluster size. If the partition is slightly out then 2 sectors will need to be accessed to get 1 clusters worth of data even though they are both the same size.

Problems arise when we start writing to the drive. When writing to SSD drives the changes usually have to be written in blocks of 4K (the smallest block size the drive can erase and change), if the cluster you are writing is not aligned to the drives sectors and overlaps into 2 of them then you will need to perform a read of the block before the changed sector and also a read of the block after the changed sector so that you know what content is to be kept as they encroach onto the changed block. You then erase the first 4K block and re-write the new data and do the same for the 2nd 4K block. With a HDD you may have to do the same BUT the sector sizes are so small you do not notice it and the drive does not have the same problems changing data as SSD does. Remember that SSD cannot change small parts of a sector, the whole sector has to be erased and re-written to change the data stored in it.

Now, if the partition is aligned then there is no need to read the cluster before and after the one being changed as the changed one fits neatly into the 4K block the SSD uses. This means changing a sector is a simple erase and then write moment, this also reduces wear on the drive as you are only changing one block.

The main problem is that XP does not understand about offsets for the partition and as such just throws them down next to each other even if they cross a sector boundary. Vista has a little bit more intelligence but is still not perfect, it will attempt to start the first partition at 64K into the drive which should improve SSD speed (but it can be improved by doing it all manually).

 

I'm still a bit confuse about the partition alignment.

If I follow this instruction on OCZ website

http://www.ocztechnologyforum.com/forum/showthread.php?p=325221#post325221

Do all the instruction on for XP Diskpar, delete partition and have it as raw.

Pop my drive back into my laptop, run the recovery CD from Sony, will I lose my alignment?

 

Ok, i see guys! Thanks.
But i don't see that as partitioning will increase performance, you're only changing the starting point and you're not partitioning it into a certain size.
It doesn't improve the actual maximum data transfer-rates?

So it's not like the case i thought and asked

Aslong as the recovery CD doesn't deletes the partition you made and creates new ones by itself, or if it reformats it by itself, but recovery CD's doesn't usualy do that. So i would say no, you won't lose your alignment.

Remeber that it only applies to XP and not Vista, as Vista will set it correct by default.

 

Vista aligns partitions to 1024 KB default when you use the Vista Installer Disk and create a new partition.

I am still curious what alignment (offset) XP SSD users use to optimize perfomance; anyone?

 

According to one of the posters here that links to a page to ocz, an alignment of 64 is enough. Allocation unit size is not the same thing as alignment though, that one they've set to 4096KB.

 

I spend all day trying to do the partition alignment, it turns out Sony restore doesn't work.

I took the drive out, put it on my desktop, format and use diskpar to change offset to 64. Put it back into my computer and restore to factory setting.

During that process, XP recovery will recreate the partition and set it back to 63. The recovery disk is not a good idea.

Going to do it again.. sigh.

 

I think best way is to do a snapshot (snapshot.exe for ex) of a working install and then create new partition aligned and the restore the snapshot you made. It is described in the ocz forums.
But I am curious of any of you Samsung owner have aligned your SSD's?