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Drobo 5C SLOW Read Speeds
05-24-2017, 05:41 AM
Post: #1
Drobo 5C SLOW Read Speeds
Hello all. I'm having a problem with extremely slow read speeds from my Drobo 5C. It;s only reading, on average, at aorund 4-8 MB/s. Write speeds are between 100-175MB/s consistenly, but the highest I've ever seen the reads go is 12 MB/s.

I've tried everything I can think of, including flipping the USB C connector over, trying a different cable, different port, etc. I've even spoent time on the phone with Drobo support, which got me nowhere.

I've had the unit in production for over a month now, so all optimization should be long complete. I have in the unit three WD Purple, 8 TB drives. All testing of the individual drives comes back ok.

Any help or advice would be GREATLY appreciated!

Thanks so much!
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05-24-2017, 03:28 PM (This post was last modified: 05-24-2017 03:29 PM by Paul.)
Post: #2
RE: Drobo 5C SLOW Read Speeds
hi carlvo,
can i check if you have constant writing to the drobo? if so, is there any way to try pausing any writing/copying to it, just to be able to try some reading tests if possible?

when you mentioned the highest read seeming to be about 12MB/s, can i check if this was on small files, or a large file? (usually smaller files will not be as efficient in most devices, than larger files).

as far as i know, each month your drobo will run some internal verifications (data scrubbing), which is in addition to the usual optimisation, and this seems to last for as long as a rebuild (at least on one of my Das drobos recently), which is about 1 day per 1TB of data (though longer if being is use)

(at the back of my mind, i seem to remember reading somewhere about purple drives as being good for constant writing (like on video camera footage), though not for simultaneous reading, though may be mistaken, but if you happen to have the model number of your model, it could be useful in trying to firm up any info about that drive?)

btw is is possible that there are some other programs using the drobo, such as mac spotlight, or window search indexing, taking place in the background, or possibly even some agressive antivirus scan schedules?

(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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05-25-2017, 07:35 AM
Post: #3
RE: Drobo 5C SLOW Read Speeds
(05-24-2017 03:28 PM)Paul Wrote:  hi carlvo,
can i check if you have constant writing to the drobo? if so, is there any way to try pausing any writing/copying to it, just to be able to try some reading tests if possible?

when you mentioned the highest read seeming to be about 12MB/s, can i check if this was on small files, or a large file? (usually smaller files will not be as efficient in most devices, than larger files).

as far as i know, each month your drobo will run some internal verifications (data scrubbing), which is in addition to the usual optimisation, and this seems to last for as long as a rebuild (at least on one of my Das drobos recently), which is about 1 day per 1TB of data (though longer if being is use)

(at the back of my mind, i seem to remember reading somewhere about purple drives as being good for constant writing (like on video camera footage), though not for simultaneous reading, though may be mistaken, but if you happen to have the model number of your model, it could be useful in trying to firm up any info about that drive?)

btw is is possible that there are some other programs using the drobo, such as mac spotlight, or window search indexing, taking place in the background, or possibly even some agressive antivirus scan schedules?

Thank you so much for your response. During testing, I have disabled all writing/reading to the Drobo. There is no reading or writing going on other than the test file. The test files I have tried are 1GB, 4GB, and 8GB, all with the same result in read speed.

The model number of the drives is: WD80PUZX. They show to have a 150MB/s sustained read rate, far above the rate I am getting. Another thing to note, I have taken one of the drives and put by itself in a cheap, $20 enclosure, and I achieve read rates over 85MB/s.

All antivirus has been turned off, there is no drive indexing going on, and nothing else to note going on that would otherwise "occupy" the Drobo.

Any further help or advice is appreciated!
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05-26-2017, 07:30 PM (This post was last modified: 05-26-2017 07:30 PM by Paul.)
Post: #4
RE: Drobo 5C SLOW Read Speeds
thanks for more info,
if you can have a look in dashboard, where it shows each drive in each bay, can you see any messages (such as if clicking on a drive bay there, or via a drop down menu), such as Warning, or Healed for any of the drives?

when you mentioned speaking with support, if you are actually still within support, it may be worth generating some diagnostic logs via dashboard, which the support team can analyse to see if any particular drive is actually possibly bringing the read spead of the diskpack down..... it was a good test that you did, trying one of the drives standalone, though in case one of the other drives was the culprit, i think a diagnostics log should be able to help capture certain info that might be able to pinpoint things...

btw how easy is it for you to try the same type of test, but by actually connecting the drobo directly to a different machine, just as a test?

(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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