I’d like to know the characteristics if the eMMC flash of the Xavier devices we will be using, in order to get a feeling of the lifetime with our current write load on the storage.
I assume (!) it’s a Hynix hbg4a2 32gb emmc flash.
I’d like to know the erase block size (I assume it’s 4 MB) and the max erase cycle count. Then i can get a feeling when we approach the wear level threshold using our write load.
Hi, the P/N is H26M64208EMRN from Hynix. There is no ‘erase block size’ and ‘erase cycle’ in data sheet, only ‘erase group size’ = 512KB. We are checking internally, you can check with Hynix in parallel.
The only info from the Hynix website
https://www.skhynix.com/products.do?lang=eng&ct1=55&ct2=57&rc=emmc_auto
is
Product Grade
AAT/AIT part is in compliance with AEC-Q100 and also developed based on the Automotive base-line.
IT part is in compliance with TS16949 and provides the same device longevity as AT parts.
Have not found any other information about this part on their website.
Also please try CMD8 and CMD9 to get CSD and EXT_CSD table for detail info of eMMC.
That shows me “only” the erase size, and in CSD_EXT the write speed, but not the number how often a block can be rewritten before failing.
That’s important to decide if an SSD/NVMe module should be added to sustain the average write load from the application for the projected lifetime of the Xavier.
There is no such number of a block in datasheet and as far as I know. In general, the P/E cycles standard are 100,000 for SLC, 3,000 for MLC and 1000 for TLC. The lifetime of eMMC is calculated based on the real P/E cycles of chip and the standard. The estimated value is stored in register of DEVICE_LIFE_TIME_EST_TYP_A/B in CSD_EXT.
The problem is that we would like top know when the flash will start to fail for a write load of
600 KBytes/minute for 12 hours and 6 days a week and we need to swap the Xavier for a new one, or if it’s cheaper to add a SSD disk or NVMe card before installing it.
You can calculate the lifetime based on 32GB, 600KB/m for 12hr x6 and P/E standard. Please search the detail calculation formula/method online.