SSDs and space economy

[DonQuigleone]

So I've recently done a big upgrade of my computer, and as part of it, I bumped my RAM up to 16 GB, and in addition to my terabyte HDD I already have, I installed a Solid State Drive, and put my main OS on it. Given my SSD is only 128 GB, I'm keen to economise. I noticed after finishing my install that there was ~30 GB of space I hadn't accounted for. I eliminated 5GB of that by taking out system restore, and another 16GB by moving the pagefile(virtual memory) from the SSD to the older larger HDD. However, I still have 8GB of unnaccounted for space. So I have 2 main questions:

1. Where is the last 8GB of space being used by windows? (IE my system says it's using 8GB more then the space if I add all my folders)

2. Was moving the page file to the HDD a good idea? On the one hand, I have a lot of RAM, and space on the SSD is limited. On the other hand, the SSD is a lot faster to read/write, so if the page file did have to be used, it would probably be better on the SSD.

[sa547]

Hmmm... Given that you're now using a huge amount of memory, maybe you should look into reducing the page file size and location by right-clicking on My Computer and then Advanced System Settings.

[spikexp]

With so much ram, you might even want to think about turning page file off.

For space, you can use spacesniffer.

[DonQuigleone]

Well right now, I moved the page file on to my HDD, where space is not really at a premium.

I'll look into spacesniffer.

[DonQuigleone]

Okay, I eliminated the last bit of space being eaten. Turns out I had forgotten to disable hibernation .

I'd still like to hear more opinions about the page file.

[Jinto]

SSD hdds have similar write cycle limitations as more common solid state memory devices like e.g. USB memory sticks. If you want to maximize the lifetime of your SSD, you would want to avoid files like the pagefile or hyperfile on the SSD. Those are very heavy duty regarding wirte cycles.

Besides, if you really ever run into a memory shortage with 16GB of RAM chances are that it is because of a memory leak of some sorts. I have 16GB of RAM in my system and disabled the pagefile. After nearly a year I never had an out of memory problem that wasn't related to 32 bit applications breaking their own 2GB addressable memory limits.

[Irenicus]

Try disable the page file and continue using your PC without worrying about it.

If you don't have problems, then you don't have problems and you've got that extra free space to put whatever you want on your Samsung. If you do just turn it back on.


That said, this is what Microsoft posted back in the very early days of SSD computing (2009):

Originally Posted by Microsoft

Should the pagefile be placed on SSDs?

Yes. Most pagefile operations are small random reads or larger sequential writes, both of which are types of operations that SSDs handle well.

In looking at telemetry data from thousands of traces and focusing on pagefile reads and writes, we find that

Pagefile.sys reads outnumber pagefile.sys writes by about 40 to 1,
Pagefile.sys read sizes are typically quite small, with 67% less than or equal to 4 KB, and 88% less than 16 KB.
Pagefile.sys writes are relatively large, with 62% greater than or equal to 128 KB and 45% being exactly 1 MB in size.

In fact, given typical pagefile reference patterns and the favorable performance characteristics SSDs have on those patterns, there are few files better than the pagefile to place on an SSD.

In other words, if you still want to have a page file, have it on your dang SSD because that's what it's good at and it is sad, very sad, when it's overly pampered by overcautious users. Cut it down to 2GB or something instead to save the space.

This was back when TRIM was young, Windows 7 was new, and many SSD's wear leveling algorithms couldn't be compared to today. Microsoft and the SSD manufacturers are much better at this SSD thing by now.

But of course having it on an HDD (so you can experience the classic slowness in Photoshop, yeah!) is different from not having the page file at all, which is a different kind of solution.

[Jinto]

Originally Posted by Irenicus

Try disable the page file and continue using your PC without worrying about it.

If you don't have problems, then you don't have problems and you've got that extra free space to put whatever you want on your Samsung. If you do just turn it back on.


That said, this is what Microsoft posted back in the very early days of SSD computing (2009):

In other words, if you still want to have a page file, have it on your dang SSD because that's what it's good at and it is sad, very sad, when it's overly pampered by overcautious users. Cut it down to 2GB or something instead to save the space.

This was back when TRIM was young, Windows 7 was new, and many SSD's wear leveling algorithms couldn't be compared to today. Microsoft and the SSD manufacturers are much better at this SSD thing by now.

But of course having it on an HDD (so you can experience the classic slowness in Photoshop, yeah!) is different from not having the page file at all, which is a different kind of solution.

Of course Microsoft does never switch off their test PCs, which explains their findings. Seriously, most other files are way more stable then the pagefile.sys. I don't know what files Microsoft used for comparison (maybe temporary files in the temp folder). The read to write ratio is completely useless unless you know the frequency of reads. If a file is read 40 times a second, with a write to read ratio of 1:40, then it will write once every second. Compare this with other files that are written only once in their whole lifetime, and maybe read once or twice a day (like most of the important system files on the drive).
Many people still do not know that producers of hard and software estimate the normal expected lifetime for consumer products to be 2 or 3 years. In their views, any operation/practice that allows hardware to at least last 3 years is good.

[Irenicus]

Originally Posted by Jinto

Of course Microsoft does never switch off their test PCs, which explains their findings. Seriously, most other files are way more stable then the pagefile.sys. I don't know what files Microsoft used for comparison (maybe temporary files in the temp folder). The read to write ratio is completely useless unless you know the frequency of reads. If a file is read 40 times a second, with a write to read ratio of 1:40, then it will write once every second. Compare this with other files that are written only once in their whole lifetime, and maybe read once or twice a day (like most of the important system files on the drive).

Well naturally, nobody could ever say that compared to most files the pagefile isn't very heavy usage. On the other hand, this is precisely why the SSD is good at it. The more reads, the more writes, the more important speed is -- especially the SSD's total superiority in random reads to the mechanical hard drives.

However, "very heavy usage" in relative terms mean little if you have a 128GB modern SSD with good controllers and you don't fill it up completely with incompressible data or something.

I would think Microsoft, having no particular major investments in the SSD industry either way but a tech support system that would be flooded with angry complaints if SSD's start dying off, would advocate an implied 3-year shelf life for storage data in a normal usage scenario. The fear is frankly overblown at this point for the average computer user, even a heavy gamer (it was more real in 2009), and things will only get better as new ECC technologies get going. Sites like Anandtech put their SSD's through hell and they come up with estimates which are comfortably far beyond the 3-years mark, even with worst case scenario data and conservative estimates of an SSD's capabilities.


But of course, as I mentioned, turning off the pagefile is also an option. Microsoft doesn't like it, but people do it often enough and their Windows don't break. I'm just sayin', if you're going to have a pagefile at all, put it in the damn SSD because that's what it's for and don't lose sleep over NAND wear. You want your day-to-day usage random access memory to be quick, that's why we have RAM in the first place. The pagefile is RAM's backup, so why go slow?

Plus, Don has a Samsung 830. Unless he's super unlucky, those things are quality. The 3000 usage cycle is conservative for the NAND flash Samsung put in there.

[DonQuigleone]

Originally Posted by Irenicus

But of course having it on an HDD (so you can experience the classic slowness in Photoshop, yeah!) is different from not having the page file at all, which is a different kind of solution.

I thought the computer would fill up the RAM before resorting to the page file (legacy 32 bit applications excepted).

Are you saying that having a page file on a hard disk could give worse performance then no page file at all.


All that said, I'll play things by ear, if I notice slow downs, I might put a small (~2-4GB) page file on my SSD.

If I have a pagefile on both the HDD, and the SSD, will the OS use the SSD page file first? Is there any way to tell it what order to use the separate page files?

Also, if I want to reenable things like Hibernate or System Restore, is there any way for me to tell the OS to put the information on the HDD rather then the SSD?

[Mentar]

Originally Posted by DonQuigleone

I thought the computer would fill up the RAM before resorting to the page file (legacy 32 bit applications excepted).

Are you saying that having a page file on a hard disk could give worse performance then no page file at all.

Under certain circumstances, this can happen indeed. Anyway, I would NOT move the page file elsewhere, this is exactly what a SSD is good for. You're throwing away a lot of your gains this way.

[gsilver]

Please do not turn off the page file. You may have far more ram than you'll ever use, but a lot of programs are written assuming that it's there.

Pagefiles require a lot of writes, which can wear out SSDs, so you were correct to move it to a traditional hard drive.

[Mentar]

Originally Posted by gsilver

Pagefiles require a lot of writes, which can wear out SSDs, so you were correct to move it to a traditional hard drive.

SSDs are specifically _designed_ to be used for stuff like page files, because they are offering extremely fast seeking times and general I/O performance. Your advice is technically absurd.

[sa547]

Originally Posted by gsilver

Please do not turn off the page file. You may have far more ram than you'll ever use, but a lot of programs are written assuming that it's there.

Pagefiles require a lot of writes, which can wear out SSDs, so you were correct to move it to a traditional hard drive.

Who said that?

[synaesthetic]

The "missing space" on a solid state drive is what's known as spare area. This is space that is set aside by the controller on the SSD to facilitate wear-leveling and other useful algorithms such as TRIM. My Intel 320 SSD is 120GB (which really means 128GB) and it's "missing" 17GB--in Windows the available space on the drive is 111GB.

There's no way to get it back, and even if you could, you wouldn't want it back. SSDs depend on spare area to ensure that the drive is written to evenly so that no NAND cells die prematurely due to uneven writes.

Mentar is also correct in that you absolutely want your swap partition or page file to be on your SSD. Nearly all writes to swap are small random writes, which SSDs excel at and will greatly improve the overall speed and reaction time of your system.

What you want to have on your SSD:

Operating system
Swap
I/O-intensive applications (web browser, Photoshop/GIMP, MS Office/LibreOffice, 7zip, development environments)

What you don't want on your SSD and can put on your HDD:

Games (they use up way too much space and don't gain any appreciable benefit)
Video
Music
Archived files (.7z, .tar.gz, etc)
Any large application that is not I/O intensive

Edit: And yes, if you have a Windows system, no matter how much RAM you have, even if you have 32GB or 64GB of RAM (though why you'd need this much I have no idea, unless you were running a lot of VMs at once), Windows will still use swap. You can't make it not use swap, and if there's no available swap, your applications will complain by going slow.

It's possible to make a Linux system operate without swap if you have lots of RAM--most Android devices do not have a swap partition, and run everything in RAM without using virtual memory at all. But I wouldn't really recommend doing it, because not all applications may be coded with no swap partition in mind.

[Wandering_Youth]

Why not try having a tiny page file on the SSD while the larger page file is on the regular HD? On my computer I got it set to 512MB pagefile for the SSD and the rest on my regular HD.

[DonQuigleone]

Originally Posted by synaesthetic

The "missing space" on a solid state drive is what's known as spare area. This is space that is set aside by the controller on the SSD to facilitate wear-leveling and other useful algorithms such as TRIM. My Intel 320 SSD is 120GB (which really means 128GB) and it's "missing" 17GB--in Windows the available space on the drive is 111GB.

There's no way to get it back, and even if you could, you wouldn't want it back. SSDs depend on spare area to ensure that the drive is written to evenly so that no NAND cells die prematurely due to uneven writes.

Well, after doing what I did, I managed to eliminate all the "mysterious missing space". You sure spare area isn't just counted as free space? (it's never a good idea to completely fill a hard drive anyway)

Though now I have a slightly different phenomenon. My folders add up to 16GB, but the SSD says only 12 GB is being occupied. Very strange.

Mentar is also correct in that you absolutely want your swap partition or page file to be on your SSD. Nearly all writes to swap are small random writes, which SSDs excel at and will greatly improve the overall speed and reaction time of your system.

What would be an adequate size? Is it possible to use swaps on the HDD and SSD in combination, with the SSD being prioritized, but the HDD swap being held "in reserve"?

What you don't want on your SSD and can put on your HDD:

Games (they use up way too much space and don't gain any appreciable benefit)
Video
Music
Archived files (.7z, .tar.gz, etc)
Any large application that is not I/O intensive

I can agree on most of those, but what about games that have a lot of loading screens? Would they get an appreciable benefit?

Also something to bear in mind is that my HDD is running on SATA 3, while my SSD is on SATA 6.

[synaesthetic]

The only appreciable benefit you'd get for games is faster loading times. Framerates would not increase.

There's an exception to this rule--the current version of FFXIV (1.23b) has a disk caching issue where it doesn't cache ahead far enough and a slow HDD can cause frame drops. Putting the game on my SSD solved the problem (mostly, anyway, it still drops frames but it's a poorly coded engine to begin with).

FFXIV 2.0's new engine doesn't have the same problem at all, so it's not a performance boost but more a bandaid on a poorly-coded renderer.

[DonQuigleone]

Originally Posted by synaesthetic

The only appreciable benefit you'd get for games is faster loading times. Framerates would not increase.

This is what I'd expect. Some games do have god awful loading times...

[Mentar]

Originally Posted by DonQuigleone

What would be an adequate size? Is it possible to use swaps on the HDD and SSD in combination, with the SSD being prioritized, but the HDD swap being held "in reserve"?

Rule of thumb for swap was twice the RAM in the past, but with the current huge sizes, I wouldn't go past 16GB max. For normal boxes, 8 should be healthy.