I would like to know the difference between hdparm's -y and -Y switches

 

one puts the drive in standby , the other in sleep

 

but what is the effect of these commands on the HD ?

 

which one of those is similar to mdcmd spindown command ?

 

and how can I awake a drive out of sleep or out of standby ?

 

thanks

I would like to know the difference between hdparm's -y and -Y switches

 

one puts the drive in standby , the other in sleep

 

but what is the effect of these commands on the HD ?

from the hdparm manual page:

-y

    Force an IDE drive to immediately enter the low power consumption standby mode, usually causing it to spin down. The current power mode status can be checked using the -C flag.

-Y

    Force an IDE drive to immediately enter the lowest power consumption sleep mode, causing it to shut down completely. A hard or soft reset is required before the drive can be accessed again (the Linux IDE driver will automatically handle issuing a reset if/when needed). The current power mode status can be checked using the -C flag.

which one of those is similar to mdcmd spindown command ?

don't know for sure, but i think it is "standby" and the IOCTL call seems to be ATA_OP_STANDBYNOW1 based on errors in the syslog when it is not supported by some hardware.

and how can I awake a drive out of sleep or out of standby ?

Access it. (read from it, or write to it)

It may b e drive / kernel / driver / controller dependent, but IIRC, I have never been able to wake a drive up from -Y without doing a power cycling of the drive.

that explains it..

 

I did a hdparm -Y , and the drive vanished... had to reboot the server

 

thanks