The complete write cycle of a flash memory consists of two stages. The number of times when erase operation on a flash memory failed. The Raw value shows the actual number of failures. When the flash memory is worn out, it cannot be written to any longer and becomes read-only. The write process is technically called "programming the flash memory", hence the attribute name. The number of times when write to a flash memory failed. The Raw value sometimes contains the actual number of used reserve blocks. The value of the attribute shows the percentage of the pool remaining. On an SSD, this attribute describes the state of the reserve block pool. The Raw value of this attribute indicates the actual event count. The number of events when internal tables of block addresses were damaged and subsequently rebuilt.
The exact values depend on a type and make of the flash memory chip. An SSD has a limit on how many times one can write to it. The total count of erase/program cycles for entire flash memory in its entire lifetime. Others conversely say this is the number of errors corrected by ECC. Some bits of documentation quote this as the number of errors not corrected by ECC and subsequently reported to the host controller. There is no certainity about the meaning of this attribute. The Raw value holds the actual number of power cycles. The value counts down, typically from 100 to 0. An SSD does not use this attribute because there is nothing to spin up.Ī Raw value typically stores the number of unsuccessful read head and positioning system calibrations.Įstimated remaining life, based on the number of power on/off cycles. For a rotational drive, this is fairly critical. The Raw value of the attribute shows the number of unsuccessful attempts to spin a spindle up to operational speed. The Raw value shows the actual powered-on time, usually in hours. The normalized value decreases over time, typically from 100 to 0. An SSD doesn’t use this attribute.Įstimated remaining lifetime, based on the time a device was powered on. There is no reliable information available about this attribute.įrequency of the errors during disk head positioning.Ĭharacterizes performance of mechanical seeks of a disk head. On an SSD, the Raw value indicates the number of failed flash memory blocks. Normalized value of the attribute decreases as the number of available spares decreases.On a regular hard drive, Raw value indicates the number of remapped sectors, which should normally be zero. When encountering a read/write/check error, a device remaps a bad sector to a "healthy" one taken from a special reserve pool. The Raw value holds the actual number of cycles. This parameter is not used with an SSD, because obviously an SSD has no moving parts.Įstimated remaining life, based on the number of spin-up/spin-down cycles. Time required a spindle to spin up to operational speed. Frequency of errors during read operations.
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