Plotting Very Slow - 5TB Seagate Drive



  • Yea, I've heard how bad Seagates are. According to haitch, they tend to break easily and are extremely slow.
    Never had one before, but I don't think I will be buying one.
    Consider getting something like a Western Digital or something else than a Seagate.


  • admin

    @p0int_scale The problem with the current high capacity Seagates is that they're SMR, which are simply painful for plotting optimized. I have two 8TB drives plotting now, and they're going to take at least another two weeks to complete. I tried plotting to a PMR drive (Seagate SAS Enterprise drive) and then copying to the SMR drives - turned out that was going to take even longer than just plotting the two drives simultaneously. So, Seagate 8TB SAS PMR drive, plotted in 16 hours, Seagate 8TB SMR drives, at least 21 days.



  • @haitch rip
    I'm impatient. Thanks for the info, was planning to buy a Seagate but I think I change my mind. With my impatience, waiting weeks to plot, I wouldn't like it at all.



  • They seem to work fine when plotted it seems, It's just the plotting that take a ridiculous amount of time to do.


  • admin

    @p0int_scale I have 18TB of SAS drives due in the next few days, will interrupt plotting the SMR drives for a day or so while I plot those. The SMR drives mine just fine, it's the plotting them that's killing me.



  • @p0int_scale said in Plotting Very Slow - 5TB Seagate Drive:

    Yea, I've heard how bad Seagates are. According to haitch, they tend to break easily and are extremely slow.
    Never had one before, but I don't think I will be buying one.
    Consider getting something like a Western Digital or something else than a Seagate.

    I have 43 seagate SMR drives, all are working like a charm. Best $/TB out there.


  • admin

    @rds Did you plot them optimized? If so, how? The ones I'm currently doing are driving me nuts with how slow they are.



  • @haitch said in Plotting Very Slow - 5TB Seagate Drive:

    @rds Did you plot them optimized? If so, how? The ones I'm currently doing are driving me nuts with how slow they are.

    hey, I'm not saying that PMR to SMR is fast but fast than straight to PMR.

    my small laptop only does ~3500 n/min on xplotter but iirc the straight to smr used to take about 2.5 days, effectively 1000 n/min because of the reduced write times to the disc.

    Writing to PMR gets me the full 3500 n/min so about 20 hours/TB. The transfer adds about 4 hours, so a day/TB. If you have a faster machine, it should scale up accordingly.


  • admin

    @rds Maybe it's a problem with these drives then. Windows was estimating 15 days to copy an 8TB plot from the PMR to the SMR. Plotting them directly, the PC can calculate at > 30,000 nonce/min, but I'm getting drive write speeds of around 5MB/sec, so effective plotting speed just sucks.



  • @haitch said in Plotting Very Slow - 5TB Seagate Drive:

    @rds Maybe it's a problem with these drives then. Windows was estimating 15 days to copy an 8TB plot from the PMR to the SMR. Plotting them directly, the PC can calculate at > 30,000 nonce/min, but I'm getting drive write speeds of around 5MB/sec, so effective plotting speed just sucks.

    yea that's 5-6 MB/sec which is the average write speed I used to see for the direct plot to SMR. When I do my PMR to SMR transfer I see anywhere from 12-100 MB/sec. 12 when the miner is scanning or other such activities are going on.


  • admin

    @rds Copying from PMR to a freshly formatted SMR, I never exceeded 10MB/s. Plotting two drives concurrently was going to be faster than plotting the PMR then copying it over. It's not a controller issue - when mining I get 400-500MB/sec throughput. I know they will mine just fine, but the plotting of them frustrates the hell out of me.



  • @haitch , strange, I am copying a file right now on the laptop from my PMR plotting drive (USB 3.0) to an SMR connected through a USB 2.0 and getting 30 MB/s, which is the max I've ever seen on 2.0. That drive is connected to 2.0 because my 3.0 controller on the laptop ran out of endpoints so I have 2-4TBs plugged into USB 2.0.



  • 0_1494858577416_upload-8611087a-4aab-4f33-bc93-1c2896281d54



  • I am now plotting with my pc on my SSD drive, writing takes just few seconds to complete. I am doing it in chunks of 100 GB and I have available like 500 GB only for the plotting space, then it's just a matter to copy them to the other drives I am going to be using for mining while keep plotting.. Otherwhise with an SMR drive will take forever to complete!



  • @vExact that's better than a PMR for sure and I have a 500GB SSD as well. I did what you did but now I don't like the tremendous amount of 100GB files (OCD). In fact, I'm now replotting all my drives from 100GB to 1 TB files. I think 1TB is the sweet spot, for me anyway.



  • I've CPU-plotted 8 SMR drives two weeks ago with 1 TiB files.
    Plot target was a PMR drive array (~6 hours/TB on 6 cores, then merge/optimize to SMR, 45 Minutes). When the SMR drives were writing, they NEVER were slower than 110 MB/s each, usually 150 MB/s.

    They're all organized in stripes (SMR: 4x 8 TB == 32 TB) and redundant Raidsets (PMR: 4+1x 4 TB == 16 TB) to not hinder data flow, but the SMR's never slowed down.

    So, it comes down to writing these SMR's strictly sequentially. That avoids the architectural speed penalty on random writes.
    Any Filesystem with frequently updated metadata areas (NTFS: $MFT — Master File Table, $Bitmap, $LogFile) is doomed here.



  • @haitch said in Plotting Very Slow - 5TB Seagate Drive:

    @rds Copying from PMR to a freshly formatted SMR, I never exceeded 10MB/s. Plotting two drives concurrently was going to be faster than plotting the PMR then copying it over. It's not a controller issue - when mining I get 400-500MB/sec throughput. I know they will mine just fine, but the plotting of them frustrates the hell out of me.

    what is the organization of these SMRs - single ?
    What filesystem ?

    I use zfs, copy-on-write it is the perfect match for SMRs.



  • @haitch Make sure disk write caching is turned on in device manager on those external drives. All of mine default to 'quick removal', which will get you deplorably slow write speeds.



  • @sevencardz ,

    I just started replotting an SMR. I decided to go back to plotting .2TB files on a 500GB SSD. I was getting 7700 nonce/min which plotted the file in 100 minutes. After the first was done and the second is plotting concurrently writing from the SSD to the SMR at 200 MB/sec.

    0_1494893711306_upload-f18f2dea-bbc8-4132-bdd3-b99a19e1ea33



  • @rds I considered using the extra 400GB of my SSD as a plot cache, but it wouldn't really be faster in my situation. It takes my system about 3 days to fill up two 8TB PMR drives with optimized plots. Then it's a little less than a day to transfer that 16TB over to two Seagate SMR drives. However, if disk write caching is OFF then I immediately notice awfully low transfer speeds of 10 - 20 MB/s. As other have stated, the SMR drives are on par with PMR drives if you limit them to large sequential writes with plenty of cache involved.

    With the GTX 1070 and the GPU plotter, I can write optimized plots to two 7200 RPM PMR drives at 25,000 nonces/minute. Two 5400 RPM PMR drives at 20,000 nonces/minute. I lose about 5,000 nonces/minute off those numbers near the end of the disks.


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