Thank you for reply Mr. Nelson, That's the simplest solution I was also thinking. Here are my timings.
# time cat /dev/mmcblk0 > /dev/null real 1m 52.01s user 0m 0.55s sys 0m 21.74s However I think I have to take care that not partitions are being erased/written at the time when I run this script, right ? On Wednesday, 20 July 2016 20:10:53 UTC+5:30, RobertCNelson wrote: > > > > On Wed, Jul 20, 2016 at 9:23 AM, Ankur Tank <[email protected] > <javascript:>> wrote: > >> >> We have BBB based custom board with 256MB RAM and 4GB eMMC running Linux >> kernel 3.12 >> >> *TL;DR*: Is there a open source application which periodically reads >> unread/rarely used partition to increase data retention? OR Is there any >> kernel service which can be configure >> >> *Detailed query,* >> We have 3 sets of partition for OS(Bootloader, kernel+dtb & RFS) eMMC. >> One of them is recovery OS. Which is rarely read( none of the time >> written). >> >> Now as per eMMC manufacturerer, >> "*If a byte is not read in 5 years there is no guarantee that byte is >> valid when read after 5 years.*" >> To avoid such situation we want to have a crawler application, which >> would read all the unused/unread partition may be once in a year and >> increase data retention. >> >> I didn't find any open source application or kernel service/daemon which >> would handle that. But not sure If I am searching it correctly or not. >> >> Meanwhile If there is no solution available for this, I am planning to do >> it in following way. >> >> 1. Setup a cron job which would trigger once in a year and run a script. >> 2. Script would read all the partition using dd and return. >> >> What do you think about this approach. >> Let me know if you have any suggestion/correction/pointers for me. >> > > > debian@test-bbb-1:~$ time sudo cat /dev/mmcblk1 > /dev/null > > real 1m20.209s > user 0m0.050s > sys 0m14.530s > > That was for a 2GB eMMC, so double the time for a 4GB.. > > But in reality, with eMMC, we are still only talking with the controller, > not directly with the NAND. So even a cat won't read every 'byte' as the > controller is doing it's own thing... > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/ad5d2b08-f70a-4cb1-a9f7-83252f076bc0%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
