Are You Killing Your SSD with Dual Boot ?

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catweazel
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Re: Are You Killing Your SSD with Dual Boot ?

Post by catweazel »

athi wrote:
Sat Sep 21, 2019 11:29 pm
As far as saving wear and tear on a SSD, use of SWAP file in place of SWAP partition allows the SSD to fully utilize TRIM and wear levelling algorithm.
FUD.

Levelling algorithms are a function of the SSD and have nothing to do with the OS or the underlying file system, consequently wear levelling in conjunction with the use of either a swap file or swap partition has nothing to do with wear levelling. As for trim, see man swapon, in particular the -d option.
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BG405
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Re: Are You Killing Your SSD with Dual Boot ?

Post by BG405 »

catweazel wrote:
Sun Sep 22, 2019 12:30 am
Levelling algorithms are a function of the SSD and have nothing to do with the OS or the underlying file system
This is reassuring and pretty much my conclusion from what I've read so far. Means not having to alter my current partition schemes when I eventually migrate to SSDs.

One question remains however; I read that it's advisable to leave some unallocated space for memory cell reallocation, is this (still?) true?

...
As for the thread title, perhaps that should read "Does dual-boot with Windows shorten the life of an SSD?" :wink:
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rene
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Re: Are You Killing Your SSD with Dual Boot ?

Post by rene »

So-called over-provisioning. Depending on the actual model of SSD, "a bit true". See, the thing is just that wear-leveling is assigning different physical sectors to the same logical sector (i.e., having potentially a different physical sector map to the as far as software is concerned same sector over time) so as to not let a write to the same logical sector end up at the same physical one each time, improving on both speed (a write of a non-empty physical sector needs a separate erase first) and longevity. For this to be possible the SSD will clearly need a pool of empty physical sectors to assign to logical sectors and this is where the over-provisioning thing comes from.

SSDs however also internally over-provision; have a reservoir of spare physical sectors that isn't available externally in the first place. How much depends on the actual model of SSD; generally one can expect the models sold as e.g 250G to have more than one sold as 256G: the latter power of two is more likely to match the actual internal size.That same reasoning would have the former already have 6G of internal over-provisioning. Admittedly that information/notion might be outdated at this point. SSD technology is moving fast --- faster than I myself am paying attention to --- but how much internal over-provisioning a drive does will certainly still be model-specific. Now that SSDs are definitively standard, I could assume that most have ample internal over-provisioning already, but still, make sure on a per-model basis.

Also note in the context of the above discussion that having unused swap in fact functions nicely as a bit of over-provisioning space already...

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catweazel
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Re: Are You Killing Your SSD with Dual Boot ?

Post by catweazel »

BG405 wrote:
Sun Sep 22, 2019 2:21 pm
One question remains however; I read that it's advisable to leave some unallocated space for memory cell reallocation, is this (still?) true?
That's called overprovisioning. Most good quality drives are overprovisioned at the factory but there's no way to tell without specialised drive software. However there is nothing wrong with leaving a few GB free at the end of the disk as a just in case. If the SSD needs that spare space, which must be at the end of the drive, the controller will use it.
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Re: Are You Killing Your SSD with Dual Boot ?

Post by rene »

catweazel wrote:
Sun Sep 22, 2019 5:01 pm
[ ... ] which must be at the end of the drive [ ... ]
This part is not the case really. Any reservoir of free blocks will do, but for example Samsung's Magician will/can create it at the end of the disk just so it can set it as a so-called HPA, Host-Protected Area; a way to have a drive "lie" as to its real capacity, thereby making sure that the additional part is really hidden from normal software (on Linux, hdparm -N manipulates the HPA). Otherwise we're in agreement, yes...

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