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Does SSD cache really speed up IO access?
09-27-2015, 07:10 AM
Post: #11
RE: Does SSD cache really speed up IO access?
(09-25-2015 04:36 AM)MoisiePants Wrote:  Hi Kirby, hi Paul:

I'm very interested to read your findings here - they seem to mirror what I was finding about 18 months ago: http://www.drobospace.com/forums/showthr...http://www.drobospace.com/forums/showthread.php

I've since been poking around on-and-off to try and find some time to investigate this further. My next aim will be to build up a Windows machine and try running the Drobo with Iometer, as Drobo demonstrate on https://www.youtube.com/watch?v=V9E2WcE_nqs (although admittedly with the B1200i, not the 5D).

I've also tried raising it with Drobo technical support, and never received a response which I could truly understand and trust as an explanation.

Fingers crossed that we finally get somewhere with this...

Thanks.


I have read your post.
I see that, you reported the transfer speed is around 300MB/s without SSD.
In my opinion, the top speed Drobo can fetch never exceed 300MB/s, so your benchmark is not meaningful.
SSD improve the IO performance mostly by saving the seeking time, not by increase the pure transfer speed.
I suggest you redesign your test. At first you must let your transfer speed become low than 20MB/s without SSD -- that must be caused by a lot of disk seeking.
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01-22-2016, 02:31 AM
Post: #12
RE: Does SSD cache really speed up IO access?
Hi, I'm trying to optimize my 5D, containing a mixed-bag of various WD totalling 18.TB of usable storage, with all drive-bays filled, AND I purchased the m480 SSD "belly plate" memory "Boost" chipset.

My question is, IF this chipset improved I/O caching, can it be setup to assist forward-caching of VLC video data---movie MKV files being "served" off the Drobo--acting as a video-server (and general file-storage "backup") I'm getting occasional "white-outs" during a video playback, were ALL the colour sort of "bleaches out", in a patchy, digital-matrix-"Garble" pattern, as (presumably) the data-stream being served (or "pulled"?) off the Drobo struggles to get ahead of the datastream, so that it will start playing smoothly-with-colour again....

Excuse my lack of "technical language", as I'm not a "back end" specialist like most of you guys in this forum!

Did I "waste" the ~$500.xx for this SSD "belly" chipset addition??? ARE there any settings to be tweaked (drivers to be upgraded for Windows.10... to smooth out the "bumps in the video playback road" I'm suffering from?? T.I.A. for any advise!

I find it strange that seemingly no DROBO tech-staff seem to do any "support" within these tech-forums... It would be very comforting to know that "driver updates", or Drobo Dashboard updates were "coming down the pipeline... Ahh welll...
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01-24-2016, 06:31 PM (This post was last modified: 01-24-2016 06:36 PM by Paul.)
Post: #13
RE: Does SSD cache really speed up IO access?
hi, it might be good to try copying one of those mkv files onto your computer,
and then rebooting the whole computer, and then trying to play that file back in vlc using the computer drive version, just to see if you still get those garbled frames?

if so, it might be due to the codec itself, rather then drobo, because usually when i have tried to play back something, it was my comptuer which was slow, and everything just slowed down, rather then to become glitchy...but you could also try using different PostProcessing options in vlc to see if it makes a difference, and could try converting that mkv into another fileformat to see if you still get errors.

having said that though, i have been able to play back dvd files i have created, directly off the drobo (including editing) without problems, and using vlc. (though i think i used the vlc portable version - maybe you can try that as it might contain all the codecs you need)

if you still get errors, even when using the local copy version, then it is probably the actual mkv file which is having a problem, and maybe related to the codec driver (vlc version) or possibly the files itself?

what happens if you also try giving vlc a higher cpu priority (such as in task manage in windows) - does that make a difference too?
for the belly plate, if that is an msata card, then i think the most benefit will be in Reading speeds, and for the smaller files, rather than for huge files.

(ideally there would be a way to specify more control over how the msata is used, but that may prove to become an interesting feature in future versions, possibly) Smile

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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03-19-2016, 11:10 AM
Post: #14
RE: Does SSD cache really speed up IO access?
From my experience (iMac connected via TB), mSATA actually DECREASED performance, or at least, performance swung wildly. Random I/O wasn't better by much and seq I/O was actually worse than without it. I could see this repeatedly.

In the end, I just took off the mSATA.
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03-19-2016, 05:27 PM
Post: #15
RE: Does SSD cache really speed up IO access?
So, this thread irked me.

Since I have been 'mad' at Drobo for a while now regarding the >16TB volume support, I was certainly looking for other reasons to be mad at Drobo.

So. I tried a completely non-scientific 'real-world' test of mSATA vs non-mSATA.

I have a 5D with 5x 4TB WD Reds. I have an Intel 525 (Lincoln Crest) 120GB mSATA which will be installed and removed for the test.

The test is run using a Mac Mini Server (Late 2012) i7 2.6GHz, 16GB DDR3 1600MHz, OS X 10.11.3.

The 5D is connected via TB.

Photos loadtime (127.8 GB library) Library loaded three times to populate cache.
w/o mSATA: 5.71 sec
w mSATA: 3.96 sec

iTunes loadtime (7.05 TB library) Again, loaded three times to populate cache.
w/o mSATA: 6.98 sec
w mSATA: 3.77 sec

I used the 'sudo purge' command between each app.

YMMV

i7 Mac Mini Server, 10.10
Drobo (Gen2), USB, 4x WD 4TB RED

Drobo (Gen3), USB3, 4X WD 4TB RED

Drobo 5D, TB, 5x WD 4TB RED, 120GB Intel 525 mSATA SSD
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03-21-2016, 09:36 AM
Post: #16
RE: Does SSD cache really speed up IO access?
hi mgriffin,
from the real world test perspective, and just to be clear, the above shows that the library loaded up more quickly with the msata then)

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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03-21-2016, 02:41 PM
Post: #17
RE: Does SSD cache really speed up IO access?
Yes. For me. With what I am sure some will point to as a flawed methodology, the mSATA improved performance.

Drobo has always maintained the mSATA assisted with multiple, small file reads/writes. For large, single file I/O, I would expect no difference.

Both Photos (and iPhoto before it) and iTunes use a database file that can easily be cached on the mSATA.

Looks like for Photos which is multiple small files (database + thumbs) the improvement was ~30%.

For iTunes, which is a large .xml file, it was ~50%

i7 Mac Mini Server, 10.10
Drobo (Gen2), USB, 4x WD 4TB RED

Drobo (Gen3), USB3, 4X WD 4TB RED

Drobo 5D, TB, 5x WD 4TB RED, 120GB Intel 525 mSATA SSD
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03-22-2016, 07:45 PM
Post: #18
RE: Does SSD cache really speed up IO access?
ok cool

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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04-28-2016, 09:17 PM
Post: #19
RE: Does SSD cache really speed up IO access?
Interesting read on Anandtech about the 5D with and without a SSD.

http://www.anandtech.com/show/10278/drob...http://www.anandtech.com/show/10278/drobo-5d-with-beyondraid-protected-directattached-storage-mad

i7 Mac Mini Server, 10.10
Drobo (Gen2), USB, 4x WD 4TB RED

Drobo (Gen3), USB3, 4X WD 4TB RED

Drobo 5D, TB, 5x WD 4TB RED, 120GB Intel 525 mSATA SSD
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05-02-2016, 03:46 PM
Post: #20
RE: Does SSD cache really speed up IO access?
that is interesting,
i think its good that they did multiple types of tests, as real usage is always worth doing, even in addition to raw benchmarks.

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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