Single SSD or Multiple SSDs?

[sydost]

Hi,

 

I am thinking about finally doing a small upgrade for my computer and take the SSD plunge. In some earlier threads there was advice of buying separate SSDs for OS and DCS. I hadn't thought about that myself. I would like to know is there real benefits of doing it that way and should I should spend some extra for two units. I could buy two 120GB Samsung 840 EVOs for 190€ or then I could get only one 250GB version for 165€.

 

Then the other question about SSDs is that should I pick the PRO model instead of the EVO. From reviews I understood that the EVO model should be quite good too. Any other brands I should consider?

[Pilotasso]

technically there isn't a reason to buy separate SSD's unless you wish to do RAID.

[Rhinox]

...I could buy two 120GB Samsung 840 EVOs for 190€ or then I could get only one 250GB version for 165€.

 

You see yourself that bigger drives usually offer better price_per_GB ratio. Except for that, 250GB is simply better than 120GB version (both of 840Evo type): has bigger cache (512MB vs 256MB), higher write-speed (520 vs 410MB/s) and higher write-IOPS (66000 vs 35000). There is no reason to buy 2x120GB. Even wear-leveling will be better handled by one big drive...

[ZaltysZ]

Larger SSDs have more chips on them, and this allows higher parallelism, what results in better performance at higher queue depths. 250GB outperforms 120GB, 500GB outperforms 250GB and so on, however difference isn't so noticeable at higher capacities as is between 120GB and 250GB.

 

If you are going for RAID, make sure your controller is able to pass TRIM to separate drives in array.

 

EVO is a bit newer, and is supposed to be an upgrade to non Pro version of 840. EVO and Pro performance is very similar in real world and even close in synthetic benchmarks. Theoretically Pro should have a longer lifespan due to usage of MLC, and not TLC, which is used in EVO. Unless you are going to do lots of writing (like in server environment), this should not be much of concern to you. Basically, if price difference between Pro and EVO looks petty to you, get Pro; if not, get EVO. :)

[sydost]

Thanks for the replys. That is pretty much how I initially thought about it to buy the single 250GB SSD. I don't intend to use RAID.

 

The reason for my question was that last night I read these threads and there was some hints that having OS and DCS on the same SSD might be a source for some stutters.

 

Here about the stutters. Reply #12

http://forums.eagle.ru/showthread.php?t=95481&page=2

 

And here on the second reply two SSDs were recommended for someone building a new rig.

http://forums.eagle.ru/showthread.php?t=116347

[HiJack]

If you go for SSD you should switch the system drive to SSD first and not simply add a SSD as single drive D: . Buy a 250GB EVO and reinstall Windows to it as the main drive on your system. Remember to deactivate DCS before starting the job ;)

[Yurgon]

Slightly OT, but the idea to get separate SSDs for OS and applications definitely reminds me of this wonderful story I read some time ago: The Certified DBA :lol:

[Yurgon]

I would have thought two separate drives would be better - Windows can do its thing with page files and behind doors business on one drive. While DCS and games sits on another drive uninterrupted.

 

The terrible thing about HDDs is that it takes ages to reposition the read/write heads on the drive. They have to physically move inwards or outwards to address specific sectors while the disc rotates below (or above) the heads. Compared to RAM, that's just incredibly slow.

 

And that's the beauty of SSDs. Without moving parts, access is so much faster - especially accessing data that is not "next to each other" on the disk (aka sequential read/write that could be relatively fast on HDDs).

 

I haven't tested this myself, but I believe the performance gain of using separate SSDs is fairly negligible and doesn't justify the additional cost compared to a single, larger drive.

 

What I've read so far in this thread seems to underline this assumption.

[ZaltysZ]

The reason for my question was that last night I read these threads and there was some hints that having OS and DCS on the same SSD might be a source for some stutters.

 

Here about the stutters. Reply #12

http://forums.eagle.ru/showthread.php?t=95481&page=2

 

Read that thread very carefully. OP of it even had stutters when OS was on SSD, and DCS was on separated disk (HDD). It was solved by changing SSD to newer one (EVO). I guess the problem has been related to TRIM implementation of that particular drive. One other poster had similar problem and it went away by disabling TRIM.

 

People concentrate on the reading part of disk usage (loading textures and etc.), but don't notice that DCS does lots of writing/reading to user home folder (temporary files, logs), which resides on OS drive by default.

[tobaschi]

buy two SSD's

 

one OS one Games

 

you will get the best result

[Bodo]

I've just bought two 256 840 Pro SSDs for my system that's currently only using one 128GB 830 SSD for the OS.

 

For me, it's about keeping the OS simply for audio applications and the main OS and usual apps, incase this goes down I don't need to worry about the reinstall as I usually save docs to a secondary HDD and/or an external drive as a backup.

 

When I have these two extra SSDs one will be for audio/photoshop work and the other, Steam games and DCS, for example, to eventually allow me to get rid of my HDDs. This will leave me with one 1TB drive that's for random stuff, films, photos, downloads etc, things that will take a lot of writes that I don't necessarily want eating in to the SSD life (although they seemingly last long enough) and files that don't exactly benefit from any performance boost, like playing films or music.

 

It's really a habit from the old days of separating HDDs so that one can do its job whilst the other does, not after that job has finished. For audio work this was absolutely necessary so that if windows started doing whatever it wanted to do, it wouldn't hinder the performance of the audio files being read from a different disk.

 

WIth SSD, this isn't necessary and it makes very little difference with regards to performance, but when it comes to backing up data, organisation and my own OCD, it helps me to have dedicated drives for specific purposes.

[SFAL]

For me the 2 seperate drive was a way to go.

 

Found a good prized samsung 128gb for the OS and got another 256gb for the rest.

 

Why? Well think of it as a redundant system. If one goes the otherone is most likely ok.

 

I havent found any performance incrace wth 2 drives. Just that comon sence dealing with windows...

[Yurgon]

Found a good prized samsung 128gb for the OS and got another 256gb for the rest.

 

Why? Well think of it as a redundant system. If one goes the otherone is most likely ok.

 

Actually, with more drives you're more likely to encounter hardware failure and thus be unable to use the OS or the applications until data is restored to a new drive. Spreading data accross multiple storage devices is the opposite of redundancy. :D

 

(With SSDs, longevity increases as write operations decrease, so the setup you describe may work or "live" longer than a single SSD setup. But that is not the definition of redundancy)

[EtherealN]

SSD longevity, aside from things like controller failure (which never was the problem anyhow), is pretty much a complete non-issue.

 

An example of this: techreport has been running an endurance test similar to those done by several other sites, since something like september. At this point, all drives have written the equivalent of doing 100GB+ per day of writes for 10+ years... And they've all got lots of spares to go. Indeed, if I remember right from when I read the last update, only the 840 even has lost sectors (but those are still within the margins given by the overprovisioning, so there's no lost data; the affected sectors were just read over to some of the overprovisioned sectors)...

 

Basically, the days when you had to worry are long over. You can use todays SSD's just the same as you previously used HDD's and you'll consider the SSD slow and obsolete way before it actually breaks down. (Aside from the normal issues that might arise from standard industrial production, but they are even less of an issue than with HDD's since there are no moving parts.)

 

EDIT: And to compare with that - my Samsung 830 has, after some 15 months of use, done a total of 5.41 TB of writes. That's with using it as the primary download location, swapfile in place, all games and programs right there, etcetera etcetera. The computer is typically always on (I don't turn it off when I go to bed, etc) It uses the same type of NAND as does the discs that, in the aforementioned test, doesn't even start to reallocate after 500TB. At this speed, I would be likely to use it for some 100 years to reach a place where I should start to worry. I think something other than write endurance will make me switch drives before then - and even if not, I'll probably die before this drive gets to the 500TB mark... :P

Edited January 13, 2014 by EtherealN

[Yurgon]

Basically, the days when you had to worry are long over. You can use todays SSD's just the same as you previously used HDD's and you'll consider the SSD slow and obsolete way before it actually breaks down.

 

Huh, good to know, thanks! :thumbup:

[ZaltysZ]

SSD longevity, aside from things like controller failure (which never was the problem anyhow), is pretty much a complete non-issue.

 

And aside from power failure :) https://www.usenix.org/system/files/conference/fast13/fast13-final80.pdf

[july865]

Buy a PCIE SSD drive. for speed of writing and reading it's the best hands down, but very pricey. jmho

[EtherealN]

Buy a PCIE SSD drive. for speed of writing and reading it's the best hands down, but very pricey. jmho

 

Usually (all I've checked) this is because they get their speed through having a high-quality RAID controller onboard. So you could theoretically get exactly the same result through getting two SATA SSDs and pairing them up with a good RAID controller. (Which may or may not - usually not - be the software RAID controller available on most motherboards. As I think someone mentioned: wants to be sure the specific RAID controller doesn't end up blocking any of the necessary functions on the SSD.)

[HiJack]

Wait for this one then!

http://hothardware.com/News/Kingston-HyperX-Predator-PCI-Express-SSD-Unveiled--With-LSI-Sandforce-SF3700-Flash-Controller/