Page files and caching SSDs (NOW URGENT!)

[Atheus]

Hi all

Might be rebuild season here again - serious storage system this time. I'm fairly sure my OS and a handful of carefuly chosen apps will be running off a Vertex 3 120GB SSD drive hooked up to a Z68 mobo for a start.

I know the Z68 can do some... magic type caching thing... via an SSD too though, so I wonder if it would be worth getting another smaller SSD, just for that caching? Funny thing is though - the larger SSDs seem faster... I can't find myself a blazing fast 16GB worth of flash. Is this something to do with the manufacturing process? Lack of a market for that stuff?

Another option is of course to get another slightly larger SSD... but then what to do with the rest of it? Page file comes to mind... but page files eat SSDs apparently so I'm not getting another Vertex 3 for that. If I put a 16 (or whatever) GB page file on a slower/cheaper SSD will that actually give me an advantage wth 8GB of RAM in there? If I 'Z68 cache' (SRT?) on a slower SSD will that actually slow down my storage system?

---

Cliffs....

1) Should I use the SRT/Z68 caching if I'm running the OS off an SSD anyway?
2) Should I get a second SSD in this build for SRT/Z68 caching? Should I use it at all?
3) Where should I put my page file? Get a second cheaper SSD just for the page file?
4) Why can't I get a 16-32GB SSD just as fast/faster than the 128s/256s?


Thanks everyone!

/edit: I'm aware of the degradation to an SSD caused by using it as swap... but could it be that bad?... The cheap drive could be considerd sacraficial... unless there are other high performance options?

 

[LokutusofBorg]

With your post count here I'm surprised you're asking about, or even mentioning, SSD lifespan. There is absolutely no sense in buying an SSD and trying to "save" it from writes. If you hammer your SSD with the max write throughput the SATA bus will allow, your SSD will still last years. Really.

The best pagefile strategy, IMO, is to go into the settings and tell Windows to use a 1GB min, <your RAM size> max, leaving everything else alone, and never worry about it again. Unless you have some crazy programs that eat up pagefile space, it'll sit somewhere between 1GB and 2GB and never grow beyond (but your settings will allow it if it ever needs to).

With a 120GB SSD you will be able to fit Windows and every application you could want to install in their default locations. (Unless you're some fringe power user that has 1000 applications that you plan to install.) Games are the exception here, in case there's any assumption I'm trying to include them in "application" (I'm not). A 120GB SSD is the *perfect* size as long as you move your Documents, Pictures, etc. folders over to your storage drive. Install Windows and all apps to the SSD. Store your games and data on your HDD.

As for SRT, unless you have some application or use case that will have your system hammering your storage drive (you're putting in an HDD as a secondary drive, right? I didn't see you mention it in your OP; SRT is putting an SSD in front of a HDD, not SSD caching for another SSD) then SRT will only net you marginal gains. Would it be worth it? It might be, given that you can buy decent SSDs for $1/GB or less lately. It'll depend heavily on your usage.

EDIT: forgot to mention. The reason large SSDs are faster than smaller ones is because the size of individual NAND dies/chips is standard, and SSDs do some pseudo-RAID0 on the inside, using all the chips in parallel. The smaller SSDs have less chips, therefore less internal RAID0-ish goodness going on. Go all the way down to 16GB and you're looking at a single NAND chip, with serial performance. This is (part of the reason) why thumb drives are slow.

 

[Atheus]

With your post count here I'm surprised you're asking about, or even mentioning, SSD lifespan.

These days I write code, not mess with performance PCs - my computers have things like redundant UPS and gas fire extinguishers rather than clocked graphics cards. If hardware goes down I call the dude at the datacenter and he fixes it for me.

I built my current gaming machine ~2/3 years ago and even that I didn't put much effort into. Used to really build PCs when I was 20 ish and when I get a chance (rarely) I still get into hardware or electronics for a a while.

Basically I don't know shit about the current state of consumer computer technology. For a programmer.

The best pagefile strategy, IMO, is to go into the settings and tell Windows to use a 1GB min, <your RAM size> max, leaving everything else alone, and never worry about it again.

Yea but this is thrashing the SSD right, like you said? The main 120GB Windows drive? Should I put it the page file on the old school 2TB HDD then? Or should I 'sacrifice' a cheaper SSD for the purpose? This was the point I was trying to make.

Also, in years gone by, it was good to have your swap on a different drive - if that still holds in Windows/latest Debian there should be performance gain just from that... but would there be more performace with 'SRT' caching on or off? Same drive, second drive, or a third drive entirely? What kind of drives? These questions plague me.

As for SRT, unless you have some application or use case that will have your system hammering your storage drive (you're putting in an HDD as a secondary drive, right? I didn't see you mention it in your OP; SRT is putting an SSD in front of a HDD, not SSD caching for another SSD) then SRT will only net you marginal gains.

I thought SRT would cache whatever the OS drive was? Is that not the case? If so that answers a lot of questions...

EDIT: forgot to mention. The reason large SSDs are faster than smaller ones is because the size of individual NAND dies/chips is standard, and SSDs do some pseudo-RAID0 on the inside, using all the chips in parallel. The smaller SSDs have less chips, therefore less internal RAID0-ish goodness going on. Go all the way down to 16GB and you're looking at a single NAND chip, with serial performance. This is (part of the reason) why thumb drives are slow.

Thanks, good info. Anyone else?

 

[razel]

There is alot of old and bad information out there. Please read our moderator ZAP's SSD primer sticky. It's got a ton of learned information. Just buy an SSD in a size you can be comfortable with and don't worry AT ALL about writes. Chances are you will upgrade before the warranty ends. IIRC, Intel's cache software will not allow an SSD cache if your main drive is an SSD. Their direct answer to *I think* Tom's Hardware was, 'It doesn't make sense.'

From what I can perceive from your arm folding and chin stroking, you seem worried about cost. The entry price point for SSDs is not $600 anymore... you can easily get it on sale for $1 per GB... at least in the US.

 

[Atheus]

Please read our moderator ZAP's SSD primer sticky.

Ok.

From what I can perceive from your arm folding and chin stroking, you seem worried about cost. The entry price point for SSDs is not $600 anymore... you can easily get it on sale for $1 per GB... at least in the US.

Actually not really worried about money atm - I'm willing to shell out the cash. The Vertex 3 drive I'm looking at is &#163;200 which isn't too bad at all.

 

[LokutusofBorg]

Like I said, if you max out your SATA bus with writes to your SSD, you will still not wear out your SSD for *years*. Normal users should not worry in any way about NAND cell lifetime.

One of the guys that works on Windows wrote a great blog post about Windows 7 & SSDs. He made the argument that SSDs kick ass at fast small (random) writes. The IO profile of the Windows pagefile is a bunch of fast small writes. Therefore, the best thing you can do for pagefile performance is put your pagefile on an SSD.

http://blogs.msdn.com/b/e7/archive/2009/05/05/support-and-q-a-for-solid-state-drives-and.aspx

The only reason you would want to put your pagefile on a different SSD is space reasons. The method I explained above about altering your pagefile settings covers that aspect. If you buy a big enough SSD (120GB or larger) I probably wouldn't even bother with that. Just let Windows manage it, and never touch it. It'll be fine.

I hope that clears things up about the pagefile.

As far as SRT goes, I think you have a misunderstanding about what it is. SRT allows an SSD to serve as cache in front of a slower drive. Putting an SSD in SRT in front of another SSD makes zero sense. It would gain you nothing. In fact it would hurt performance.

If you buy a non-crappy SSD and pair it with a good 7200 RPM HDD you'll be fine. If you're really determined to max out the performance of your storage drive, then sure, putting an SSD in SRT in front of it would help.

 

[Atheus]

Okay just a few final points I swear...

As far as SRT goes, I think you have a misunderstanding about what it is. SRT allows an SSD to serve as cache in front of a slower drive. Putting an SSD in SRT in front of another SSD makes zero sense. It would gain you nothing. In fact it would hurt performance.

If you buy a non-crappy SSD and pair it with a good 7200 RPM HDD you'll be fine. If you're really determined to max out the performance of your storage drive, then sure, putting an SSD in SRT in front of it would help.

1) If I put my OS and 'apps' on a Vertex 3 120GB, then can I put a smaller SSD in front of a WD Cavair Green HDD as SRT... like set it to a specific drive? Then I get SSD speedup for my games on the WD HDD too.

2) Is there really no point in swap file on seperate drives? It'll be on a different channel so it'll be faster than boot drive right? Or is this old school thinking? I don't understand how this works these days... I could even turn off page ebtirely since I'll have 8GB RAM.. but there might be sine situations the system need page file...

3) Will the OS ignore the page fille so long as some of my 8GB RAM is available? So it shouldn't get much use right?

BTW I'm buying this machine NOW so I need replies! Thanks everyone.

/edit: typos and more info

 

[ViviTheMage]

You could...but I just put STEAM/games on a mechanical drive, they load fast enough for me.

I also have pagefile turned off ... 16GB of memory is going to waste

 

[Atheus]

You could...but I just put STEAM/games on a mechanical drive, they load fast enough for me.

I also have pagefile turned off ... 16GB of memory is going to waste

I guess I could go 16GB... I suspect that'll reduce my memory bandwidth in games though...

Do you actually use the whole 16 if the page file is turned off, or would 8 do? I'm looking at overclockable 8GB kits.

 

[dbcooper1]

Just put the pagefile on the SSD; it used to be put on a different physical drive to avoid seek contention with mechanical drives.

 

[Binky]

1. No
2. No
3. On the SSD
4. Bigger is always faster (and bigger)

 

[exdeath]

I guess I could go 16GB... I suspect that'll reduce my memory bandwidth in games though...

Do you actually use the whole 16 if the page file is turned off, or would 8 do? I'm looking at overclockable 8GB kits.

X79 soon, problem solved.

 

[fuzzymath10]

I don't think the lifespan rule applies to POS indilinx drives with huge WA. My smart data says that my ssd has logged 3500 out of 5000 writes on average per cell after only 8-9mo of typical use. While 5000 is an arbitrary number, it illustrates how fast some drives accumulate writes. My intel SSDs average only several hundred wriites per cell over 2 years and I have no comfort issues with those.

 

[Fallen Kell]

The reason the bigger SSDs are "faster" is because the number of physical chips of memory used are typically higher than the smaller drives. More chips means more bandwidth since the reads/writes are spread across all the chips in sequence (think of each chip as a disk in a RAID 0 strip, the more disks you have, the faster it will be).

That is why when all the newer higher density memory chips came out using the 25nm lithography process, doubling the memory per chip, all the drives which switched over to using these new chips had serious performance hits compared against similar sized drives using the older 32nm chips (and why Anandtech had several articles on the front page about it as several companies didn't even change their product name/SKU and there was no way to determine if you had an older drive which were the ones first benchmarked by all the tech websites, or the new drive which had a good 40-50&#37; performance hit... ***COUGH*** OCZ ***Cough*** Vertex 2 ***COUGH***)

 

[Elfear]

You should check out this thread over at XS. A couple guys over there decided to see how long various SSDs would last using an app that just writes data to the drive all day long. They used CrystalDiskInfo to measure how quickly the SSD was wearing out. The parameter used is called the Media Wear Indicator (MWI) and measures the life expectancy as a percentage. I don't know all the ins and outs but it somehow measures the available life of the NAND.

As you can see in the charts there, most of the drives had 170-300TB written to them before the MWI went to 0%. That would be equivalent to writing 20GB per day for 23-41yrs. However, the drives continued to work after the MWI had reached 0%. In fact one drive had 478TB written to it before it died. That would be 20GB per day for 65.5yrs.

I wouldn't worry too much about thrashing on your SSD. :biggrin:

 

[Dadofamunky]

I also wouldn't get too twisted up about caching architectures and such. The Intel flash caching scheme, on the few reviews I've read that discuss it, say it doesn't add much compared to simply booting off an SSD and loading apps off of it. If I were you, I'd just get as big of a high-quality SSD as I could justify for my boot disk, and get a couple 2 TB spindles and RAID those. End of story. And keep the Windows caching defaults or something close to what others say upthread. Since I can load Photoshop and Illustrator more or less instantly on my system, I feel justified in saying you'll be delighted with the performance you get. You won't get enough benefit doing anything more complicated.

 

[Dadofamunky]

And, since you're a coder not a gamer, concentrate on system throughput - beefy CPU, 16 GB of RAM, an SSD and RAIDed spindles - and you'll have a screaming rig that will last you for five years. You'll compile stuff instantly and your interpreters will run so fast you'll wonder if something is wrong.

 

[Voo]

You'll compile stuff instantly and your interpreters will run so fast you'll wonder if something is wrong.

Neither compiling nor interpreting (huh?) stuff is particularly IO limited, so no you won't see any particularly impressive gains for the vast majority of projects.

 

[tweakboy]

If you have 4GB or less of RAM then you need a system page file. If you have 8GB or more you dont need a page file, its all in RAM. thx gg

pointless to put a page file on SSD, it wont get used,, you have enough RAM. turn off page file this is not 2GB ram days.

IMO A SSD thats 300GB so I can put my whole C on it. Use other drives as backups and what not.