Functional Description
Data Retention
Data retention refers to the SSD's media (NAND Flash) capability to retain programmed
data when the SSD is powered off. The two primary factors that influence data retention
are degree of use (the number of PROGRAM/ERASE cycles on the media) and tempera-
ture.
Degree of use: As NAND Flash is used (programmed and erased), its natural ability to
retain charge (programmed data) decreases. When the SSD ships from the factory, it is
typically able to retain user data for up to 10 years when powered off. As the SSD is used,
this typically decreases to one year.
Temperature: As the temperature increases, data retention decreases.
Note: All data retention related to values in the data sheet are with the SSD powered off.
When the SSD is powered on, data retention is expected to exceed these limits. Micron
SSD data retention with power removed is one year at 40°C (MAX).
Micron RAIN Technology
Redundant array of independent NAND (RAIN) is a technology developed by Micron
designed to extend the lifespan of the P320h.
Residing in the P320h ASIC controller, RAIN is similar to redundant array of independ-
ent disks (RAID) technology, but instead of grouping and striping disks, RAIN groups
and stripes storage elements on the SSD across multiple channels, generating and stor-
ing parity data along with user data (one page of parity for every seven pages of user
data). This data structure (user data plus parity) enables complete, transparent data re-
covery if a single storage element (NAND page, block, or die) fails. If a failure occurs, the
P320h automatically detects it and transparently rebuilds the data. During this RAIN re-
build process, the drive's performance is reduced temporarily but will recover after the
rebuild process completes.
Wear Leveling
Wear leveling is a technique that spreads Flash block use over the entire memory array
to equalize the PROGRAM/ERASE cycles on all blocks in the array. This helps to en-
hance the lifespan of the SSD. The P320h supports both static and dynamic wear level-
ing.
Static wear leveling considers all Flash blocks in the SSD regardless of data content or
access and maintains an even level of wear across the drive. Dynamic wear leveling
monitors available free space on the drive and dynamically moves data between Flash
blocks to equalize wear on each block. Both techniques are used together within the
controller to optimally balance the wear profile of the Flash array along with the drive's
lifespan.
P320h HHHL PCIe NAND SSD
Functional Description
PDF: 09005aef848cbdf4
realssd_p320h_hhhl_distribution.pdf - Rev. V 8/2014 EN
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© 2011 Micron Technology, Inc. All rights reserved.
