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Samsung 830 + Samsung 840 Pro

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January 23, 2013 11:59:18 AM

Let's suppose that I'm about to make a RAID set of Samsung 830 and Samsung 840 Pro.
I'm using a MacBook Pro 13 inch 2012 model, with core i7 and 8gb of ram.
I'm gonna rip out the superdrive to make space for a second ssd.
Here are the two drives I'm using for my RAID array:
Samsung 830 128GB--- Read: 420mb/s Write: 325mb/s (0.15W)
Samsung 840 Pro 128GB---- Read: 498mb/s Write: 390mb/s (0.15W)
I really need the answers to these questions, as Google wouldn't tell me

1) What size should my RAID block be, if I'm wanting a balance between performance and low power consumption?
2) What is the estimated speed of my raid array?
3) My MacBook Pro has 63W, 5750mah battery, is this set up THAT bad for the battery health/life?
4) Will this setup decrease my battery life by more than 1 hour?

I know that these are tough questions, but I really seek the answers, so please answer.
January 23, 2013 12:35:32 PM

so you decided to ignore the advice given in one question, then go ahead and ask for advice about how to best set up the thing that you were advised against doing... i am confused as to why you ask.
January 23, 2013 12:43:06 PM

Your battery life will be fine, in fact you will probably barely even notice a difference with a second SSD.

Why do you want to raid two SSD's? I would keep them separate.
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January 23, 2013 12:47:20 PM

Thank You for your answer!!
I wanna set up raid 0 just because of my curiosity and my desire of greater performance.
I have a time capsule so I don't have much risk of losing my data.

Could someone please tell me the estimated speed of this RAID setup?
January 23, 2013 1:17:50 PM

ok so here's how it will go: in theory, to get this working to it's full potential, you would need to create an asymmetrical RAID 0, whereby it send smaller data chunks to the slower drive, and larger chunks to the faster drive. this would stop the 830 being throttled and the 840 pro under-performing. the only problem, is that there is no such thing as an asymmetrical RAID 0 configuration, software or hardware. the best thing you can do is to check what size chunks you would use for the 830, and set them both to that. only problem with that is, as stated, you would lose the performance boost that the 840 pro would give you and not actually gain any speed over having one large 830.

if you want a viable option for running the two together, it would be to run them separately. have the 840 pro with your OS and boot and critical software, and the 830 as storage.

as for battery life, warhead0 is quite right in saying that it wouldn't have a massive effect on your battery life, but there will be a difference. you are accessing two drives rather than one, after all.
January 23, 2013 1:20:24 PM

oh and i forgot to mention, if you are using two different SSDs in RAID you can run into a problem with the controller if you are using hardware to RAID the drives (some controllers just plain refuse to do it, due to the inner tech being different, i.e. the 840 uses TLC, whereas the 830 doesn't). the other thing that can happen is that you will lose the TRIM function completely.
January 23, 2013 1:28:17 PM

phate1337 said:
oh and i forgot to mention, if you are using two different SSDs in RAID you can run into a problem with the controller if you are using hardware to RAID the drives (some controllers just plain refuse to do it, due to the inner tech being different, i.e. the 840 uses TLC, whereas the 830 doesn't). the other thing that can happen is that you will lose the TRIM function completely.


This made the things much more clear:
Thank you phate 1337, i will not set up this raid thing, it sounds dangerous....
January 23, 2013 1:36:05 PM

you are very welcome
a b Ô Samsung
a c 353 G Storage
January 23, 2013 2:45:07 PM

1) Generally Using two diff drives (same size, different speed) should not be an issue for raid0
2) performance wise, somewheres between the two as individual drives would run are their own speed.
3) overall performance gain (vs two separate drives) will be very user dependent.
.. A) Raid0 will boost Sequencial performance, but does nothing to improve access time, not improve random 4 K performance.
.. B) For boot time and program load times - NO real life performance gain as this relies mostly on access time and 4 K random performance - SEQUENCIAL performance has little bearing on this.
.. C) Sequencial performance Only improves for read/writes of LARGE file files. ie editing the large bitmap/jpeg photos and manipulating large movie files (DVD file normally is 1 gig, and a single blueray file can be up to 40 gigs.

For the above reasons, I normally only recommend raid0 if you do a lot of work with these large data structures, and the files are on the ssd. Myself, have dual SSDs in two desktops and one laptop - I discontinued using raid0 when I switched to SSDs.

4) as stated above, the addition of the 840 pro will not adversely effect battery on time. The 840 Pro has about the lowest power drain of SSDs @ idle (.3 Watts) and only draws about 3 -> 3.2 Watts for read/writes.
Ref: http://www.anandtech.com/show/6428/corsair-neutron-neut...
January 24, 2013 7:10:13 AM

Thank you RetiredChief
a b Ô Samsung
a c 353 G Storage
January 24, 2013 10:51:20 AM

akirarsah - On Trim. Correct on loss of Trim with Raid0 with a Mac: Note: Trim is now supported by on a Intel 7 series MB using latest Intel driver when SSD is a member drive of a raid set-up.
Not sure if mac OS supports trim for Non-raid configuration, probably does.
January 24, 2013 11:01:55 AM

hmmmm
I know this app called trim enabler...
but what good does that do? will it improve the Random access time or something?
!