Estimating flash life by reading EC (Erase Counters)

Estimating flash life by reading EC (Erase Counters)

[David Yat Sin]

Hi,
My goal is to be able to estimate the flash drive life in a production
environment, so if there is a better/easier way of achieving this,
please let me know.

I have a small embedded device using NAND than runs UBIFS for the user
partition. Our application constantly writes to log files, the log
files are appended and gzip'ed, so it is hard to determine how much
data is actually written to disk.

I am hoping to do this by:

1. Read the EC (Erase Count) headers for each page on the partition
2. Let my system run for several days/weeks/months
3. Read the EC headers again
4. Then extrapolate drive life expectancy by comparing number of erase
counts with the NAND endurance.

Is there a utility that I could use to read the Erase Counters on a
UBIFS partition?

Thank you
David

Re: Estimating flash life by reading EC (Erase Counters)

[Richard Weinberger]

On Mon, Apr 21, 2014 at 9:41 PM, David Yat Sin <jd.yatsin@gmail.com> wrote:
> Hi,
> My goal is to be able to estimate the flash drive life in a production
> environment, so if there is a better/easier way of achieving this,
> please let me know.
>
> I have a small embedded device using NAND than runs UBIFS for the user
> partition. Our application constantly writes to log files, the log
> files are appended and gzip'ed, so it is hard to determine how much
> data is actually written to disk.
>
> I am hoping to do this by:
>
> 1. Read the EC (Erase Count) headers for each page on the partition
> 2. Let my system run for several days/weeks/months
> 3. Read the EC headers again
> 4. Then extrapolate drive life expectancy by comparing number of erase
> counts with the NAND endurance.
>
> Is there a utility that I could use to read the Erase Counters on a
> UBIFS partition?

IIRC ubinfo can tell you the value of the highest EC.

-- 
Thanks,
//richard

RE: Estimating flash life by reading EC (Erase Counters)

[Mats Kärrman]

On Monday, April 21, 2014 10:48 PM, Richard Weinberger wrote:
> On Mon, Apr 21, 2014 at 9:41 PM, David Yat Sin <jd.yatsin@gmail.com> wrote:
>> Hi,
>> My goal is to be able to estimate the flash drive life in a production
>> environment, so if there is a better/easier way of achieving this,
>> please let me know.
>>
>> I have a small embedded device using NAND than runs UBIFS for the user
>> partition. Our application constantly writes to log files, the log
>> files are appended and gzip'ed, so it is hard to determine how much
>> data is actually written to disk.
>>
>> I am hoping to do this by:
>>
>> 1. Read the EC (Erase Count) headers for each page on the partition
>> 2. Let my system run for several days/weeks/months
>> 3. Read the EC headers again
>> 4. Then extrapolate drive life expectancy by comparing number of erase
>> counts with the NAND endurance.
>>
>> Is there a utility that I could use to read the Erase Counters on a
>> UBIFS partition?
>
>IIRC ubinfo can tell you the value of the highest EC.

Same value can be found using:

cat /sys/class/ubi/ubi0/max_ec

As you probably know, both max and mean value can be found in the kernel message log after a reboot, e.g.:

UBI: max/mean erase counter: 10/7

BR // Mats