My 1/2 PetaByte



  • @ChuckNorris said in My 1/2 PetaByte:

    stagger 10000

    Your files have a stagger of 10000, that means

    10000 * 64 Bytes == 640 KBytes can be read sequentially, seek to pos + ((640KBytes*4095)), repeat until end.

    You should definitely optimize your file if you want to increase read-speed per disk.
    What that means for your overall performance - i can't say. Do it for one of the miners.

    With a plot size of 7.4TiB you will have a stagger of

    7.4 TiB / 4096 / 64 Bytes == 31037849

    and that gives you a sequential read for

    31037849 * 64 Bytes == 1.986 GBytes

    Your disks will read much faster as A LOT LESS seeks are performed.

    (read ~2 GBytes in 640 KByte chunks: (31037849 * 64 ) / (640000) == 3103 seeks PLUS metadata lookup
    time per seek: 10 ms
    3103 * 10 ms == 31 Seconds just for head movement)



  • @vaxman @gpedro Very helpful guys. I was already going to optimize of course. There was never a thought that i wasn't. I was just saying i just now got my drives buffered. And no. I can't write direct. It's 4 times slower. there is an explanation if you want it.

    It's nice to see all the math tho. Thanks for that. I'm still filling up drives. About 80tb a day at this point. I'll be ready to throw the petabyte online within the next week. Then as it's mining optimize the drives over the course of another month.



  • Wow, that is a beautiful farm you got there. I am currently looking to build a 100TB farm but the external hard drives are quite expensive here in Estonia. About 30$ per TB is the cheapest one and this is with 20% discount i get thanks to my friend.



  • What a wonderfull farm :)
    Which rule you follow for USB hub? 7 drives per port?



  • @agente Yeah. I know 7 drives per hub isn't optimal. But at the same time. I'm reading 250tb in 60 seconds on unoptimized plots. And also it keeps the cost down.



  • but do you mean that each hub is like a separate external device, connected to the usb on the mainboard?

    Or do you use separate PCI-E usb hub for each 7 drives?



  • @axadiw96 7 hard drives per hub. Each hub has it's own dedicated usb host controller with a usb expansion card



  • ok, and what kind of expansion cards are you using exactly?

    Actually could you describe your miner setup (CPU, GPU if you're using jminer, RAM etc.)? You've said that you're using separate machine every 250TB's, right?



  • @axadiw96 Well. At least a reply 3 months later is better than no reply at all. Haven't been around here. Damn attackers have took down the forums for a while

    -It's an i7 7700
    -32gb ram (only need 16gb)
    -i run 7 usb 8tb seagate drives per hub (Should be 4-5 per hub)
    -I run one usb controller card. Card has 1 controller per usb port

    Results. 250tb per machine. Read time 60 seconds. Still optimizing drives. Opt should cut it down to 40-45 seconds
    Secondary results. Have another farm i built for someone. 400tb per machine. 70-80 second read time. Don't recommend as much. Machine can crawl too. Pushed the limits to hard on that one.



  • thanks @ChuckNorris

    Which miner are you using? If you're using some GPU assisted one, which GPU you have?:)

    You've said that you're using usb controller card with separate controller for each usb port. Which one - Sonnet Allegro Pro?