09-14-2011 03:30 AM
I cannot find any specific information on the M4's nand page size and nand erase block size. I need them in order to aligh the partitions of my server's disks. The server has three M4 units, one 64GB, another 128GB and the last one 256GB. I plan to install Gentoo Linux, which has no installer, you need to create the partitions manually, using fdisk and setting the starting/ending cylinders of each parition.
Can anyone provide me the actual valoes of the page size and erase block size for the three M4 models? Is it the same for all of them?
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09-14-2011 03:53 AM - edited 09-14-2011 03:54 AM
On 25nm NAND (which the drives use) the page size is 8k.
I've never seen the erase block size specified. All MLC SSD's I'm aware of have an erase block size of 512k so I assume it's the same here? The Erase block size doesn't affect alignment anyway though.
09-14-2011 04:21 AM
Thanks for your answer, targetbsp.
I have to say I'm totally new to SSD alignment, but all articles and forums post I've read talk about erase block size as an important parameter for alignment. Even the online calculators use to include it
09-14-2011 05:03 AM
I think it's back from the days before trim and Garbage Collection was handling the erases for us. The date of that linked page is old now for instance. The more modern benchmarking tools (AS and Anvil) only check the page alignment.
09-14-2011 05:16 AM
If you round your partition offsets up to the nearest MB you won't go far wrong. 1mb is a multiple of 4k, 8k, 512k and will also cover you in case the erase size doubled to 1mb (when the page doubled from 4 to 8) and if it does turn out to have a benefit.
Windows starts its paritions at either 1mb or 101mb depending on how it's set up.
09-14-2011 08:19 AM
One correction to the information here. The page size is based on the density of the NAND not the process geometry. The 64GB and 128GB m4’s utilize NAND with 4K page sizes and the 256GB and 512GB m4’s utilize NAND with 8K pages.
09-14-2011 08:40 AM
Thanks for clarifying that! I'd read that in one place somewhere and every other time I'd googled it the reviewers were implying a blanket 8k. I thought I'd imagined the size difference!
09-14-2011 10:10 AM - edited 09-14-2011 10:13 AM
it is for this reason that the 64 GB and 128GB are more efficient on the 4k,
09-15-2011 06:24 AM
Thanks all for the answers.
After more research now I see targetbsp was right, the erase block size has nothing to do with the partition alignment. However, it is necessary to know it in order to 'align' the file system.
Can anyone confirm the erase block size for the M4 models is 512K?
08-12-2014 02:23 PM