single SATA-3 vs. dual SATA-2 in RAID 0?

I've seen some cheap Kingstons going for $1/gig. Can anyone speak to possible advantage vs. disadvantage of going RAID-0 instead of one expensive SSD at 6gbps?

Losing TRIM would be an obvious minus. Anything else?

 

Reliability. 2 drives has twice as much failure rate. Since it is Raid-0, everything will be gone.


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If that's it, then I have to think this is the best way to up random 4K numbers or incompressible sequentials.

 

Lack of trim may seem insignificant, but the other methods that aid against ssd degrading are not near as effective and require constant use.

Raid 0 will generate close to, or same as double speeds as a sata II, but it's not really worth it IMO. An OCZ Vertex 3 Max IOPS can run as fast as two Vertex 2s in Raid 0, without the fuss or RAID issues.

 

Cheap Kingstons in RAID0 vs. a single good/modern SSD?

How much time do you have?

The single SSD (I'm thinking 250GB or larger) will be much more resilient/reliable than the small/tiny 'old tech' SSD's that will still not match it for performance - even with a dedicated, high-end RAID controller.

If you consider tearing down, SE'ing and rebuilding this system every few months (6 months is too long... I'm sure...) and will be doing this anyways (regardless of RAID0 SSD's or not), then this is not a disadvantage to you.

If, you are building this system to produce (work) with, then even a minute of downtime is a 'con' to the 'pro' of using SSD's in the first place.

 

Random write goes up in RAID, random read doesn't. Personally I'm much more interested in read performance because 8 out of 10 times I'm waiting for a job to finish it's the read speeds that are bottlenecking.

Here's a review for 2x X25v vs. X25m
AnandTech - Intel X25-V in RAID-0: Faster than X25-M G2 for $250?

 

Good responses. If random read doesn't go up, then I don't really see the point of doing this, unless it's super cheap of course.

EDIT: Actually, I just read Anand's review:

"Random read performance didn't improve all that much for some reason. We're bottlenecked somewhere else obviously."

So, maybe there's hope after all.

 

if there's no bottleneck, everything should go up, but one thing won't get better: latency. that will be actually a bit worse due to the raid controller intercepting the data stream. i'm curious what the latency increase of a typical raid controller is. it never mattered for hdds, obviously. but now having 0.065ms latency, and not >=7ms, it starts to might have a negative impact.

 

Okay, but here's what I'm saying. Even if I don't match a SATA III drive, perhaps I can get close to a good SATA 2 drive at $1/gig.

In my experience with SSD ownership, the things that affect speed seem to be random read and queue depth. Does latency figure a big part in that?

 

This review does show a good improvement:
Corsair Force 90GB SSD Single & RAID Review - Page 7

 

latency plays a role everywhere, especially in small things. so yes. but as i don't know the impact of latency, i can't say it matters if it's raid0 or singledrive.

question is, how good the ssd will handle the different write patterns a raid0 setup pushes. and how good they will live over time without trim.

 

If you buy an SSD with good GC the TRIM issue should be covered.

 

sure. but he's locking at cheap ssds. so, there goes that..

 

Kingston V series are the cheap ones he's considering, I believe they have decent GC but I'm not sure.

 

The ones he wants is the Kingston V+100's - 'super GC' at the cost of high power consumption (when pushed) and also high WA ratio.

The benefit of these SSD's? No visible degradation no matter how hard you hammer them (until they die, of course).

See:
AnandTech - Kingston SSDNow V+100 Review

 

so it will mean (combined with the raid controller and the fact that there are two ssds running) very high power consumption as the main loss compared to a single sata3 ssd. performance should be in a similar league, if the raid controller can deliver.

 

Yeah the Kingston V+ have good GC but they're not that cheap. That's why he's looking at the V series. The older V series have horrible power consumption, the newer have improved.

 

No, power consumption will be higher (even with no RAID controller card), performance will still be below the single / better SSD and I'm not even sure he can use a SATA3 SSD in his system.

What he will get though is the most consistent performance from those RAID0 Kingston V+100's (from the very aggressive GC) - even if it may be sometimes lower than the flucuating performance of the top 'benchmark king' SSD; the V3.

 

consider what phil said. the V and the V+ are not the same.

i said power consumtion == raid controller + 2x ssd => higher than a single ssd.

you can't talk about ssd performance anyways (and it would in that case be very raid controller dependent).

 

Yeah, I can talk about the SSD performance of the Kingstons - they're not up to a single (250GB or larger) single drive yet. Even in RAID0. No matter what controller you use.

Especially if the original 'V' and not the 'V+100' is considered.

 

what do you base that on? specs?

 

Even the relatively slow Kingston V series blows away the WD Black 750GB.

 

not for tiller, and you know that. he'll prove that again after this weekend. can't wait. it'll be hilarious

 

I was thinking the V+
There was a deal for 64GB at $64 with rebate. I figured two of those would be decent. Deal has s ince expired, but will probably pop up again.

So, ultimately the V+ is worth it then?

 

Yeah even one of them is quite fast, see Techreport.com. Two should be really fast.

 

Here's what happens with two C300 128GB in RAID 0 on SATA II.


Not bad. 4K read hasn't really improved but 4K QD32 did big time.

 

I wonder how important those QD32 numbers are. A few weeks into using my Intel X25-M over my Vertex 2 for my OS drive, it's pretty clear that the Vertex 2 is faster in general. I haven't figured out whether it's because of Random 4K or QD32.

 

The average workload is everything from QD0-7ish I think. The heavier workload, the more queues.

AnandTech - OWC Mercury Extreme Pro 6G SSD Review (120GB)
AnandTech - OCZ's Vertex 2 Pro Preview: The Fastest MLC SSD We've Ever Tested

 

sweet sweet.

still can't beat a single laptop harddrive /sarcasm.

(can't wait for tillers report on how bad ssds really are after this weekend. i hope obama reads it in his next message to the world, as, you know, it's real, and truth, and important! ).