Recent content by sambrightman

Ok, this is the key. My assumption was that (data) page size was an integer multiple of cell size. Physical page size is an integer multiple of cell size, remaining cells after the data page size are used for ECC/admin. The SLC cache benefit in terms of admin and latency is clear to me...

I think we agree on all of this. I said in the post you reply to that this seems likely to be dealt with by cache and has more downside by increasing wasted space if you would try to match. Alignment is much more important, and that's why I'm trying to understand if TLC drives have every second...

I'm not following where you disagree with me. There is an integer number of cells per SSD page, the cells are 3 bits, therefore the pages are multiples of 3 bits. These are the actual pages that the controller must eventually read or write from, and their size does not change. You seem to agree...

Potentially you would get some benefits to having e.g. 8K filesystem blocks on an SSD with 8K NAND pages. One FS write of 8K would be one SSD write instead of 2. However, seems like this is *very* likely to be solved with the controller cache anyway (and you waste more space on files smaller...

That is exactly what I'm asking. It is not clear that this is the case with Samsung TLC. Contrary to what you suggest in your previous post, SSD page size is part of the physical architecture of the NAND and cannot change as the controller sees fit. If there are 3 bits per cell and X cells per...

I don't agree this is deep knowledge that only a controller programmer knows. Look at the depth that the average Anandtech review goes into. It is even stated in the 840 EVO review (although possibly incorrect), along with much deeper information. I would like to get this right, get the most...

Several reviews - including Anand - have mentioned TurboWrite on Samsung 840 EVO and newer drives increasing performance. Nobody appears to question to what extent the SLC zone wears out, since it is dealing with every write to the disk in a concentrated area. I also note that the endurance...

I don't think anyone doubts the value of alignment. The disk knows nothing of partitions and cannot wait indefinitely for another write that fits the gap. Furthermore, the next gap will then need filling too. The odd thing here is not actually having the details of the "geometry" to calculate...

What makes you think the hardware and driver can optimise for odd-sized or misaligned pages/blocks? That doesn't sound possible to me.

Another user claims to have got the EBS direct from Samsung technical support: https://bbs.archlinux.org/viewtopic.php?pid=1385980#p1385980 They have just flat-out refused to give me the information via e-mail. They claim Windows 7+ does it automatically, which is obviously not true (it...

There are quite a few references on the web to the Samsung 840 & 840 EVO having an unusual erase block size of 1.5MiB due to TLC (and page size 8KiB). I assume this applies to the 850 drives too. This would mean that most often-quoted alignment information for them is incorrect ("Windows 7+...