I recently got a Samsung SSD. I have debian wheezy installed on it. I carry it around in a USB enclosure and boot both my work and home computers from it. How can I ensure that the system properly powers down the drive during shutdown? The following SMART metrics seem to indicate that it doesn't:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 24 235 Unknown_Attribute 0x0012 099 099 000 Old_age Always - 23
I believe the numbers indicate the drive has been powered up 24 times and has lost power unexpectedly 23 times, i.e. every power down. The metrics are described on Samsung's website as follows:
ID # 12 Power-On Count
The raw value of this attribute reports the cumulative number of power on/off cycles. This includes both sudden power off and normal power off cases.
ID # 235 Power Recovery Count
A count of the number of sudden power off cases. If there is a sudden power off, the firmware must recover all of the mapping and user data during the next power on. This is a count of the number of times this has happened.
I read that unexpected power loss is bad for an SSD.
Edit: Now I'm not sure this is a real question. I tried attaching the drive to a different system, putting it to sleep with
hdparm -Y /dev/sdX, and then disconnecting the USB cable. It still increments the power recovery count. I tried this with three different enclosures. I think I'll take this issue to Samsung.