Swap partition on 19NM Toggle NAND SSD's
Posted: Sat Feb 16, 2013 4:25 pm
In purchasing a new SSD recently, I discovered something interesting, and perhaps problematic for some Linux users.
SSD NAND is getting thinner, and with that, the maximum P/E cycles or endurance for these chips is reportedly getting shorter. For example, one manufacturer went from a maximum of 5,000 P/E cycles to 3,000 P/E cycles to now about 500 P/E cycles for its newest SSD. The newest SSD utilizes a 19nm Toggle NAND whereas the earlier SSD's use a 24nm MLC NAND. As an aside, apparently there are no endurance measures given in P/E cycles for the new 19nm NAND and instead a new endurance measure for these SSD's is given in Total Bytes Written (e.g., for one new 60 Gb 19nm NAND SSD, the advertised TBW is 32 TB.) Total Bytes Written or TBW as defined as "how much total data can be written to an SSD for a given workload before the drive reaches its endurance limits." Doing the math that comes out to about 500 P/E cycles.
I've read the discussions concerning swap partitions, size and whether they are needed. One point seems to have a consensus, and that is, if you hibernate your computer, you need a swap partition equal to 1x to 2x the size of your RAM. In addition for all SSD's, the manufacturers state not to defragment the drive. It shortens the SSD's useful life.
So here's the question. With the trend of SSD's going to thinner NAND and as such, shorter endurances, whether it's measured in P/E cycles or TBW's, isn't a person who hibernates his computer each day going to shorten the life of his SSD, probably more so than defragmenting from time to time? For example with a swap partition where nearly all the memory is written to daily and with an SSD having a maximum of 500 P/E cycles, it seems that the SSD, at least the memory in the swap partition, is going to be unreliable in about 16 to 18 months. A shortened reliability would be the case as well where the swap partition is being heavily used during normal computing. Are these observations valid or will the "wear leveling" features of the SSD controller prevent this from happening?
I do not use "hybernation" and use "suspend" instead. But I do have a typical swap partition for daily computing on the contingency that it's needed although I personally have never seen the swap partition used. As such, I intentionally bought an SSD with an advertised endurance of 3,000 P/E cycles or about 6 times the reliability based on the advertised TBW of the new 19 nm NAND SSD's.
One last point. I've seen different manufacturers give 3 and 5 year warranties for SSD's that use the same new 19nm NAND chips. This difference in warranties is puzzling to me. I would rather have an SSD that I know will last rather than have one where its lifespan is "iffy" but the manufacturer gives a good warranty.
SSD NAND is getting thinner, and with that, the maximum P/E cycles or endurance for these chips is reportedly getting shorter. For example, one manufacturer went from a maximum of 5,000 P/E cycles to 3,000 P/E cycles to now about 500 P/E cycles for its newest SSD. The newest SSD utilizes a 19nm Toggle NAND whereas the earlier SSD's use a 24nm MLC NAND. As an aside, apparently there are no endurance measures given in P/E cycles for the new 19nm NAND and instead a new endurance measure for these SSD's is given in Total Bytes Written (e.g., for one new 60 Gb 19nm NAND SSD, the advertised TBW is 32 TB.) Total Bytes Written or TBW as defined as "how much total data can be written to an SSD for a given workload before the drive reaches its endurance limits." Doing the math that comes out to about 500 P/E cycles.
I've read the discussions concerning swap partitions, size and whether they are needed. One point seems to have a consensus, and that is, if you hibernate your computer, you need a swap partition equal to 1x to 2x the size of your RAM. In addition for all SSD's, the manufacturers state not to defragment the drive. It shortens the SSD's useful life.
So here's the question. With the trend of SSD's going to thinner NAND and as such, shorter endurances, whether it's measured in P/E cycles or TBW's, isn't a person who hibernates his computer each day going to shorten the life of his SSD, probably more so than defragmenting from time to time? For example with a swap partition where nearly all the memory is written to daily and with an SSD having a maximum of 500 P/E cycles, it seems that the SSD, at least the memory in the swap partition, is going to be unreliable in about 16 to 18 months. A shortened reliability would be the case as well where the swap partition is being heavily used during normal computing. Are these observations valid or will the "wear leveling" features of the SSD controller prevent this from happening?
I do not use "hybernation" and use "suspend" instead. But I do have a typical swap partition for daily computing on the contingency that it's needed although I personally have never seen the swap partition used. As such, I intentionally bought an SSD with an advertised endurance of 3,000 P/E cycles or about 6 times the reliability based on the advertised TBW of the new 19 nm NAND SSD's.
One last point. I've seen different manufacturers give 3 and 5 year warranties for SSD's that use the same new 19nm NAND chips. This difference in warranties is puzzling to me. I would rather have an SSD that I know will last rather than have one where its lifespan is "iffy" but the manufacturer gives a good warranty.