two SATA III SSDs in RAID 0 vs two SATA III SSDs and two mSATA in RAID 0

fcar1999ta · Jun 23, 2015

So, I am getting a new laptop. I already have two Samsung Pro 128GB SSDs that I am going to set up in RAID 0..... .but... what if I add two 128GB mSATA drives and have a 4 drive RAID 0?

The manufacturer said that it appears that the mobo will support this setup, but they have not tested it.

other specs:
i7 4810
32GB 1866 RAM
dual GTX 970m
120hz screen

drtoast · Jun 23, 2015

Why are you raiding SSD's for the love of god.

fcar1999ta · Jun 23, 2015

I have tested one vs two in RAID 0. RAID 0 boots faster. I am looking for input from someone who has compared 2 RAID 0 SSDs vs 4 RAID 0 SSDs. Please refrain from posting anything that you have no direct knowledge of.

utgotye · Jun 23, 2015

Is there enough difference between one and RAID 0 to justify the cost? A couple seconds isn't worth the time, effort or expense. Patience is a virtue.

Where does the laptop come into play?

USAFRet · Jun 23, 2015

fcar1999ta :

Slightly different, but RAID 0 vs no RAID 0.

http://www.tomshardware.com/reviews/ssd-raid-benchmark,3485.html

utgotye · Jun 23, 2015

USAFRet :

Boss. Proof that it's a complete waste of time and money.

fcar1999ta · Jun 23, 2015

That supports my findings with one drive vs two drives in RAID 0. I want to see results with 4 drives in RAID 0.

utgotye · Jun 23, 2015

If that .7 secs is that important to you then I suggest that you test it and find out.

USAFRet · Jun 23, 2015

fcar1999ta :

I think you'll find the number of people that have done a 4x SSD RAID 0 with 2 x SATA drives and 2 x mSATA drives, in a normal everyday use laptop, and have posted the results somewhere, is about 0

Buy it, test it, post the results.
Someone has to be the guinea pig.

Solandri · Jun 23, 2015

RAID 0, much less RAID 0 with 128 GB SSDs, is pointless unless your workload consists of lots of reading big data files. Something like real-time video editing.

The 128 GB SSDs generally have half the lanes (half the flash packages running in parallel) as the 256 GB SSDs, so are already considerably slower. Putting two of them in RAID 0 basically puts you even with a single 256 GB SSD, except you now have the overhead of software RAID instead of all of the parallelism being handled by the drive's hardware.

Drive speeds are measured in MB/s. This is unfortunate because your perception of drive speed is actually the inverse - sec/MB aka wait time. This means the bigger MB/s gets, the less difference it makes. If you need to read 1 GB of data:

100 MB/s HDD = 10 sec
250 MB/s SATA 2 SSD = 4 sec
500 MB/s SATA 3 SSD = 2 sec
1 GB/s RAID 0 SSDs = 1 sec

See how each doubling of MB/s results in only half the improvement in wait time? Compared to a HDD, a SSD on SATA 2 saves you 6 sec. Going to SATA 3 saves you just 2 more sec. And going to RAID 0 only saves you 1 more sec. In other words, the majority of the speedup from switching to a SSD is obtained by a single SSD on SATA 2. And the vast majority of the speedup by a single SSD on SATA 3. RAIDing them gives very little improvement in wait times.

Furthermore, these MB/s are only for sequential read/writes of large files (e.g. real-time video editing). The vast majority of computer read/writes are of smaller files. And even the fastest PCIe SSD still maxes out at around 40 MB/s read and 100 MB/s write on 4k files. RAID 0 actually makes those slower, because since 4k is the smallest read/write a drive can do, both drives are still dealing with 4k of data. And the system overhead of RAID 0 slows things down more than if you were read/writing 4k data with a single drive.

Unless you're doing real-time video editing or something similar, don't bother wasting time with RAID 0 with SSDs. Your best performance at present is with a 500GB or 1TB SSD.

fcar1999ta · Jun 23, 2015

utgotye :

so basically, you have no idea, and are speaking out of your ass. Thanks for being useless.

USAFRet · Jun 23, 2015

Let's keep it civil in here, shall we?

fcar1999ta · Jun 23, 2015

Solandri :

RAID 0, much less RAID 0 with 128 GB SSDs, is pointless unless your workload consists of lots of reading big data files. Something like real-time video editing.

The 128 GB SSDs generally have half the lanes (half the flash packages running in parallel) as the 256 GB SSDs, so are already considerably slower. Putting two of them in RAID 0 basically puts you even with a single 256 GB SSD, except you now have the overhead of software RAID instead of all of the parallelism being handled by the drive's hardware.

Drive speeds are measured in MB/s. This is unfortunate because your perception of drive speed is actually the inverse - sec/MB aka wait time. This means the bigger MB/s gets, the less difference it makes. If you need to read 1 GB of data:

100 MB/s HDD = 10 sec
250 MB/s SATA 2 SSD = 4 sec
500 MB/s SATA 3 SSD = 2 sec
1 GB/s RAID 0 SSDs = 1 sec

See how each doubling of MB/s results in only half the improvement in wait time? Compared to a HDD, a SSD on SATA 2 saves you 6 sec. Going to SATA 3 saves you just 2 more sec. And going to RAID 0 only saves you 1 more sec. In other words, the majority of the speedup from switching to a SSD is obtained by a single SSD on SATA 2. And the vast majority of the speedup by a single SSD on SATA 3. RAIDing them gives very little improvement in wait times.

Furthermore, these MB/s are only for sequential read/writes of large files (e.g. real-time video editing). The vast majority of computer read/writes are of smaller files. And even the fastest PCIe SSD still maxes out at around 40 MB/s read and 100 MB/s write on 4k files. RAID 0 actually makes those slower, because since 4k is the smallest read/write a drive can do, both drives are still dealing with 4k of data. And the system overhead of RAID 0 slows things down more than if you were read/writing 4k data with a single drive.

Unless you're doing real-time video editing or something similar, don't bother wasting time with RAID 0 with SSDs. Your best performance at present is with a 500GB or 1TB SSD.

I have seen data the seems to show that two SATA3 SSDs in RAID 0 read/write at speeds in the range of 9-10Gbps. One SATA3 drive runs 6Gbps, and 12 SATA3 drives in a non RAID will run at 6Gbps.

This data suggests that four SATA3 SSDs (SATAIII or mSATA) would RAID 0 at close to 20Gbps.

20Gbps vs 6Gbps.........................................

USAFRet · Jun 23, 2015

For certain, limited, use cases, yes. A RAID 0 with SSD's can be faster.
Moving large sequential files from one array to another, for instance. A render farm for a 3D movie, perhaps.

Normal everyday use is just the opposite. Many, many tiny random reads and writes. In which case the RAID 0 doesn't do a whole lot. Then add in the RAID overhead, and it may well be slower.

But...Buy it. Test it. Show us. We might all be wrong.

utgotye · Jun 23, 2015

fcar1999ta :

Thanks for the laugh.

fcar1999ta · Jun 27, 2015

I got a smoking deal on two 128GB Samsung 850 Pro.... like 15% less than one 256GB and free shipping. That is why I went with two 128GBs. Now the laptop production is on hold due to a power failure during the custom builder's testing. The more time I have on my old laptop, the more I want faster and faster. I guess I figure I am just about maxing everything out, why not run 4 SSDs in RAID 0 too.

I dunno... I might if I can get a good deal on two mSATA 120-128GB SSDs.

Solandri · Jun 27, 2015

fcar1999ta :

I'll give this one last try.

Gbps and MB/s is what you should use to measure if you have a fixed amount of computer time, and need to try to get as much data as possible read in that time. For example, you have 50 seconds before the computer blows up, and you need to transfer its drive data to a flash drive ASAP. That's the type of situation where you should think about drive speeds in terms of Gbps or MB/s. This type of situation is almost never relevant. Reviewers and drive manufacturers just like measuring things this way because it results in very big numbers for very small improvements in performance.

sec/GB is what you should use to measure if you have a fixed amount of data to read, and you want to know how much time it'll take to read it. Almost everything you do with a computer is this type of situation. To boot Windows or start a game, the computer needs to read a fixed amount of data off the drive. And what you care about is how much time it takes to do that.

(HDD) 100 MB/s = 10 sec/GB
(SATA 1) 150 MB/s = 6.67 sec/GB
(SATA 2) 300 MB/s = 3.33 sec/GB
(SATA 3) 600 MB/s = 1.67 sec/GB
(2x RAID 0) 1 GB/s = 1 sec/GB
(4x RAID 0) 2 GB/s = 0.5 sec/GB

The max speedup you'll see going from 600 MB/s to 2 GB/s is 1.17 sec per GB. That's less than the 1.67 sec per GB speedup you got going from SATA 2 to SATA 3. And less than 1/8th the speedup from a HDD to a SATA 3 SSD. You're basically going through all this trouble so you can reduce your wait times by at most an extra 12% over the reduction you got switching from a HDD to a SSD.

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two SATA III SSDs in RAID 0 vs two SATA III SSDs and two mSATA in RAID 0

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