On Tue, 27 Apr 2021, Kent Watsen wrote:
* FWIW, the Intel DC 3700 SSDs are 400 GB, and hence too big for a single ZIL/SLOG. Thus I partitioned each into six 60 GB partitions. I’m using one pair of 60 GB partitions for the SSD-based pool's slog, one pair for the HDD-based pool’s slog, and the remaining four GB partitions are held in reserve for when the first two wear out.
That is interesting. However, I doubt that the device is aware of your partitions. The device only knows about sectors.
NAND flash needs to be erased in large blocks of a given size (e.g. 128k), which might include multiple/many sectors. Blocks must be erased before they may be written.
The flash wear leveling (moving data to fresher erasure areas) is done by drive firmware and it considers the whole drive. Given this, holding partitions in reserve in case others wear out does not make sense. Creating an "unused" partition can assure that this part of flash is not directly used, and thus make more available for wear leveling if the device does not reserve enough spare space. In reality the device would be swapping lightly used regions for heavily used regions by copying data. The "unused" space may actually be used.
Bob -- Bob Friesenhahn [email protected], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ Public Key, http://www.simplesystems.org/users/bfriesen/public-key.txt ------------------------------------------ illumos: illumos-discuss Permalink: https://illumos.topicbox.com/groups/discuss/T6ef0a71646a80e63-M924604b09e2f29decfddce5b Delivery options: https://illumos.topicbox.com/groups/discuss/subscription
