Fastpath..

[SteveRo]

what mbreslin said is absolutely correct.
Of course the downside is that this is a major time drain.
I am doing exactly this (all this week) to find the sweet spot of # of drives/stripe size/allocation size.
So many variables - you (and all of us) need time and patience to find that sweet spot.

[mbreslin]

Which is why you won't see me benching anymore, tuning was becoming too much like actual work. This hobby is supposed to be fun!

[SteveRo]

Starring at the pcmv hdd test progress wheel can be almost hipnotic

[AceNZ]

I could be wrong, but my understanding of FastPath is that it increases the maximum IOPS that the controller can execute, but that it has little, if any, effect if you're running below the max. For a 2-drive array at 250 MB/s for 4K/QD32, you're already running at 64000 IOPS, or 32000 per SSD. That's close to Intel's 35000 spec (which you might reach with a slightly higher QD). I doubt you'll see any improvement from FP until you hit around 90 or 100K IOPS--so somewhere between 3 and 4 Intel SSDs.

[GullLars]

Actually, you can see an improvement in accesstime, and how quickly the array scales with QD.
I suggest running the last config i posted (1 worker, 4KB random read, QD 1-32, linear 1 QD steps) and posting the results before and after fastpath so i can plot the scaling to illustrate.

[Computurd]

AceNZ if you look at the reuslts above it scales rather quickly with the low QD numbers. that is the attraction! the 35k number you are speaking of is with high QD. you can do it with QD of 4 on a FP enabled card.

[mbreslin]

Starring at the pcmv hdd test progress wheel can be almost hipnotic

Yes! And you drive yourself crazy thinking it seems to be going slower/faster than last time. So many times I've sworn it was taking much longer and yet I got a better score than ever before.

Nothing is worse than the full pcmv suite failing after an hour+ on the last gaming test. I'm so nervous every time on that part.

[Computurd]

i noticed you do full runs on your submissions. i never do full runs takes too long i dont think ive done a full run in the last hundred or so...

[AceNZ]

AceNZ if you look at the reuslts above it scales rather quickly with the low QD numbers. that is the attraction! the 35k number you are speaking of is with high QD. you can do it with QD of 4 on a FP enabled card.

In this thread? Can you tell me which post you're looking at? In #83, comparing mbreslin's 8R0 FP vs. noFP with 1W, the benefits at QD=4 look pretty minimal to me, and the big benefits don't seem to kick in until 60K IOPS or so.

http://www.xtremesystems.org/forums/...2&postcount=83

Also, if the perf at QD=4 is better with FP, then why are trans am's CDM results so similar with and without FP? Are you saying the improvement shows up in latency measurements, but not throughput?

[GullLars]

The improvements in latency translates to improved small block throughput. The large block throughput is virtually unaffected by NAND latency and is highly dependent on internal stripe sizes and parallelization.
FastPath also seems to enable further scaling past about 80-100K IOPS, but that's not a relevant case for most common user scenarios, since it's mostly above QD 24-32.
There should be a graph you can look at for scaling at QD 1-8 that i posted, if you look at that, you'll se FP helping out.

[Computurd]

here is 4k scaling before and after

AFTER .................................................. .................................................. ..... BEFORE

[SteveRo]

Paul - should your caption read "after vs before"?
Also, very nice improvement! 122K - very nice!

[Computurd]

yea i was thinking that actually when i posted oh well figured it was self explanatory! i am very impressed with the performance would love to get some newer drives....but must wait...

[Wintel64]

How to confirm the Fastpath has been enabled?

Can check it in LSI Web BIOS?

[Computurd]

nope. the only way to tell is that yer latency goes down to .08-.09 area. also your small file random will skyrocket. if you are gettting over 150 mb/s at any queue depth on 4k random, i would say its working.

[mbreslin]

The way to know for sure is to download megacli (link), then in an elevated command prompt type MegaCli fwtermlog Dsply –a0 > fw.log. In the log you will see something about upgrade key being detected, if you don't I would contact LSI.

[Computurd]

nice tidbit! didnt know that, thanks for sharing!

[m.oreilly]

http://www.lsi.com/DistributionSyste...ws_MegaCLI.zip
working link

[mbreslin]

@m.oreilly: Thanks! Updated my link above as well.

[AceNZ]

The 9260-8i and the 9261-8i are supposedly the same controllers, except for connector location/orientation. In that case, it should be possible to use FastPath on the 9261, right? Unfortunately, this isn't covered in the docs or on the LSI web site. Does anyone happen to know where the FastPath would attach on the 9261?

[mbreslin]

This may not help but, since you have both, look for those kind of inverted plastic back clip things that hold the key in place. One of those should be fairly obvious somewhere on the card.

(I kind of assume you've already looked and if you can't find one it doesn't seem likely that it's compatible)

Lastly try to contact LSI, depending on time of day/phase of the moon/god knows what else I receive responses from them anywhere from a few hours up to about 2 days, good luck.

[Anvil]

I'm still waiting for my FP Key

By the time I order the next FP Key it'll probably be offered as a software download.

[dwayneberry]

Hi,

I am pleased to see the good results others are seeing with there fastpath keys installed.

I have been asking LSI evern since getting this setup going about very poor random small I/O. It seems a bit rude that they are choosing to seel us an add on to get the performance that we were initially sold the cards to expect...

Here is my current 128K sequential read 128QD IO meter


Here is my current 4k random read 128QD IO meter


I am hoping to get x4 on the 4k read with the new fast path keys.

What did people see with the write rates with the fastpath key?

[Anvil]

dwayneberry,

what is your config, drives etc?

[Computurd]

yes dwayne please tell...3808 mb/s!! wow!!