September 20, 201015 yr I'm using the same exact power supply that Tom put's into the MD-1510, the Corsair CMPSU-650TX with the 52 Amp Single Rail 12V supply. Due to the recent rash of sale prices on both 2GB and 1.5GB drives I decided to fit out my unRaid with a full case of drives. So my server now has 17 total drives in it. Does this power supply have enough juice to power this many drives. Here is why I ask..... I was able to add 5 new drives to the system with no trouble, all of the new drive are 100% empty. Just for shits and giggles I decided to run a new parity check today and at about 5% complete the parity checked stopped and the 14th data drive came up disabled. I ran the Smart check and it came back good so I did the "Trust the Parity Drive" process and it all came back just fine. Tried to run another parity and drive 14 once again came back as disabled after the parity ran for a little while. Could actually be that this drive although new could be bad but I'm thinking power. Any thoughts.....
September 20, 201015 yr I'm using the same exact power supply that Tom put's into the MD-1510, the Corsair CMPSU-650TX with the 52 Amp Single Rail 12V supply. Due to the recent rash of sale prices on both 2GB and 1.5GB drives I decided to fit out my unRaid with a full case of drives. So my server now has 17 total drives in it. Does this power supply have enough juice to power this many drives. Here is why I ask..... I was able to add 5 new drives to the system with no trouble, all of the new drive are 100% empty. Just for shits and giggles I decided to run a new parity check today and at about 5% complete the parity checked stopped and the 14th data drive came up disabled. I ran the Smart check and it came back good so I did the "Trust the Parity Drive" process and it all came back just fine. Tried to run another parity and drive 14 once again came back as disabled after the parity ran for a little while. Could actually be that this drive although new could be bad but I'm thinking power. Any thoughts..... Did you run preclear on any of these drives before you added them to the unRAID array? If not i would suggest doing that to see if disk14 can even clear a preclear session. Oh, and to answer the original question... You should be able to run 17 drives off of that PSU.
September 20, 201015 yr Author When you say run a pre-clear I'm assuming that you're speaking of the "clearing" process of writing all zero's. If that's what you're asking then yes but frankly there is no other way that I know of to add a new drive, right...?
September 20, 201015 yr He's talking about using the community script called "preclear_disks.sh" http://lime-technology.com/forum/index.php?topic=2817.0
September 21, 201015 yr The rule of thumb is that green drives use 2A each and 7200rpm drives use 3A each. So your 52A PSU could support up to 26 green drives or 17 7200rpm drives. You could also run a mixture of both, just add them up and make sure they don't surpass 52A.
September 21, 201015 yr Start-up current is much more correlated to the drive maker than the spin speed. Start-up current for popular unRAID hard disks. Information taken from the following: http://www.xbitlabs.com/articles/storage/display/15-2tb-hdd-roundup_18.html#sect0 http://www.xbitlabs.com/articles/storage/display/2tb-7200rpm_18.html#sect0 http://www.xbitlabs.com/articles/storage/display/1tb-2tb-roundup-2_16.html#sect0 Start current for 12 volts 5400-5900 rpm 2TB WD Green 1.41 or 1.51 2TB Samsung F3 1.46 2TB Seagate LP 2.34 7200 rpm 2TB WD Black 1.60 2TB Hitachi 7K2000 1.91 2TB Seagate XT 2.39 Drive manufacturer has more to do with start-up current requirements than rpm. Other than the 12 volt rail supplying the motors for the hard disks, you also must account for the motherboard and the hard drive electronics, neither of these are trivial. I think a more accurate way to select a drive is to pick a power supply with a single 12 volt rail. Allow 50 watts for the motherboard and 20 (Western Digital and Samsung) to 30 watts (Hitachi and Seagate) per drive. In the above situation 17 drives would require between 400 and 560 watts. This is a very conservative estimate because it is based on the measured peak current draw when starting the system up. The peak for each device does not occur at the same time.
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