I have 7 hard drives (window 7)

I'm wondering if your power supply may not be large enough. Drives can pull quite a lot of power (over 20 watts) when they first spin up, and with seven drives they could be trying to pull between 100 and 200 watts and not getting what they need.

If you have all of the drives connected to the same power line from your power supply and you have other, unused lines you might want to try reconnecting half your drives to another line.

Have you tried using another SATA cable and/or SATA power cable? If it still happen try using another hard drive, and if it still happens, it most likely that you have insufficient power supply,

WD Green consume 6 Watt, WD Blue 7 Watt, WD Black 10 Watt.

Those ratings are for continuous power during normal operation. The drives consume considerably more power during the first few seconds as they spin up. For example, the spec sheet for the WD10EARS (1GB Green "Advanced Format") drive shows that it has a peak power draw of 1.75A from the 12V supply. 12V x 1.75A = 21 watts.

Unfortunately the spec sheet I have for the black drive doesn't list peak power consumption, but you can expect it to be proportionally more than the green drives.

I believe sminlal is on the right track. If you are finding the harddrives are showing up but no particular ones all the time then you probably have a peak power issue. Try upgrading to a larger power supply.

If it is a power issue, it's possible that simply redistributing the drives across more power rails will be sufficient. For example if the power lines for all the drives are plugged into a single power supply connector and if that particular power supply rail is rated at only 100 watts, then splitting the drives across two 100 watt connectors may be all that's needed. It all depends on how the power supply is designed and how much draw there is by the other components of the system.

+1

Try this first. Have you tried each drive individually to make sure they work and don't disappear?

im using a corsair 450w with 7 hdd's no issue - i'm thinking more drivers, assigning (raid/normal etc) or power (connection) issue - if its a power issues its more likely *ALL* the drives and even more likely the entire system will not function correctly, rather then 1-2 drives.

HDD's don't consume that much power seriously.

Different power supplies have different designs. For example your 450W supply may provide a single rail of 12V power that's shared among all of it's connectors. In that case, there won't be any problems unless the total draw of all the components exceeds the total 12V current rating.

Other power supplies have separate 12V rails with a lower current limit on each one. In that case, too much draw on any one connector can cause problems while having no effect on equipment that draws from the other connectors. See: http://en.wikipedia.org/wiki/Power_supply_rail#Multiple...

It's quite possible that the OP's problem isn't power related, but given the symptoms it seems to be the most likely issue to me and that's the first thing I'd check. Seven hard drives do draw a substantial amount of power for the first few seconds that it takes them to spin up. During that time if they draw more 12V current than the power supply rail is designed to provide then it could result in a low voltage condition. (The power supply is supposed to shut down if that happens, but not all power supplies are that smart.) A low voltage on the 12V line might well cause the drive itself to shut down so as to prevent damage caused by platters that aren't spinning fast enough to provide a stable air bearing for the heads.

Hi all
thank you for replies  
you probably are right that my power supply may not be large enough.


I replaced sata cables places on motherboard and changed drive disk letters names.
I hope that the last instruction solved this problem


http://en.kioskea.net/forum/affich-47589-disk-drive-not...

http://www.itechtalk.com/thread3400.html



just follow the instruction

go to start
right click on my computer
click on manage
then click on storage
then click on disk management
then right click on your device and select add letters and path
window will pop up then click on add
the select an alphabet and click on ok

this will solve your prb....


until now I can see all my hard disk drivers .
thank you

Hi sminlal
you are right cuz you said to me that my power supply may not be large enough.
the last instruction that i wrote did not work and i sometimes one of the hards or two disappeared suddenly in front of my eyes. this convinced me that you are right.
now I use 5 hdd's only , and I diconnected the other 2 hards and kept them as backup
thank you