Best SATA drive for FreeNAS SLOG - Intel S3710 or S4600?

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lunadesign

Active Member
Aug 7, 2013
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What's more important for a FreeNAS SLOG drive, lower latency or higher write performance?

Consider the following:

Intel S3710 200 GB
Seq Read = 550 MB/s
Seq Write = 300 MB/s
Random Read = 85,000 IOPS
Random Write = 43,000 IOPS
Read Latency = 55 us
Write Latency = 66 us
Lifetime Writes = 3.6 PB

Intel S4600 240 GB
Seq Read = 500 MB/s
Seq Write = 260 MB/s
Random Read = 72,000 IOPS
Random Write = 38,000 IOPS
Read Latency = 36 us
Write Latency = 36 us
Lifetime Writes = 1.4 PB

(Read specs are probably meaningless for a SLOG drive but I'm listing them here for completeness.)

Note that the newer S4600 has much better latency specs but the older S3710 is somewhat better in the rest of the specs.

I'm not concerned about the difference in the Lifetime Writes spec as both figures seem sufficient for my needs.
 

i386

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Mar 18, 2016
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Hmm, sadly I don't know how a slog device io looks like (10% read, 90% write at 4k?).

My guess is that unless you push many small iops the s4600 with it's lower latency will perform better at low qd.
 

Rand__

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Mar 6, 2014
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usually latency is key for slog.
Have not seen any benches for the S4600 but if you buy new why not consider Optane 900p (if you got a slot to spare)
That one is definetely very good.
 

lunadesign

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Aug 7, 2013
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Hmm, sadly I don't know how a slog device io looks like (10% read, 90% write at 4k?).

My guess is that unless you push many small iops the s4600 with it's lower latency will perform better at low qd.
If I'm not mistaken its 100% write (except when it gets read when recovering after a crash or unexpected power off situation).
 

lunadesign

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Aug 7, 2013
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usually latency is key for slog.
Have not seen any benches for the S4600 but if you buy new why not consider Optane 900p (if you got a slot to spare)
That one is definetely very good.
Unfortunately, I'm out of slots or else I totally would! :(
 

lunadesign

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Aug 7, 2013
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I ran dskspd with a mixed (80/20) , 4k random iops workload a while ago: https://forums.servethehome.com/index.php?threads/intel-dc-s3710-discontinued.14911/#post-171979
The s4600 outperformed the s3710 in total iops.
This is very helpful. I had actually started that thread but I missed your follow-up with the perf numbers. If I look at just the write numbers, the S4600 beats the S3710 except, interestingly enough, in latency (assuming I'm reading it correctly). What kind of system / OS did you run the tests on? I wonder what it would look like in an 100% write scenario....
 

jkjk

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Mar 10, 2018
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Nobrainer.
Optane is the way to go here.
In this scenario, I can't see nothing beating it.
 
Jul 14, 2017
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Any idea if there's going to be a significant difference between the 58gb and 118gb Optane 800P as a SLOG?

I'm looking at it for about 16 gb of storage.
 

sth

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Oct 29, 2015
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I always understood for a ZIL PLP, i.e reliability was more important than speed/latency. I use a S3710.
 

ServerSemi

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Jan 12, 2017
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I think a cheap optane drive is the better option. Or see if you can get a 900p 280gb which is not that expensive for what it offer.
 

i386

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Mar 18, 2016
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I always understood for a ZIL PLP, i.e reliability was more important than speed/latency. I use a S3710.
:confused:
These are kinda two pair of shoes:
PLP saves your data in a blackout.
Latency & throughput define how fast the logical device will be when using sync writes
 

sth

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Oct 29, 2015
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No ones debating these are different aspects but when asking "What's more important for a FreeNAS SLOG drive", not considering PLP and data reliability seems remiss. A fast car with inappropriate brakes doesnt go fast for very long in my teenage experience.
 
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T_Minus

Build. Break. Fix. Repeat
Feb 15, 2015
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No ones debating these are different aspects but when asking "What's more important for a FreeNAS SLOG drive", not considering PLP and data reliability seems remiss. A fast car with inappropriate brakes doesnt go fast for very long in my teenage experience.
Agreed. But the drives he's already decided on, and asking about do have those things so bringing it up and saying it's more important than performance... well sure, but kind of irrelevant in this thread ;)

These 2 devices each have PLP and End-To-End Data protection it's not really a talking point for this comparison, IMO.

My vote is for optane :D too!
 

modder man

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Jan 19, 2015
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Can one of these optane drives be used in a PCI-E adapter on an older supermicro x9 machine?