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m (Fix remark on M.2 SSD data buses to acknowledge SATA versions exist.) |
m (Update remarks on flash pages) |
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As of 2014, most NAND-flash SSDs on the market have 8192-byte page sizes. However, models using 128-Gbit NAND from certain manufacturers have a 16384-byte page size. Maximum performance requires that vdevs be created with correct ashift values (13 for 8192-byte and 14 for 16384-byte). However, not all Open ZFS platforms support this. The Linux port supports ashift=13, while others are limited to ashift=12 (4096-byte). | As of 2014, most NAND-flash SSDs on the market have 8192-byte page sizes. However, models using 128-Gbit NAND from certain manufacturers have a 16384-byte page size. Maximum performance requires that vdevs be created with correct ashift values (13 for 8192-byte and 14 for 16384-byte). However, not all Open ZFS platforms support this. The Linux port supports ashift=13, while others are limited to ashift=12 (4096-byte). | ||
As of 2017, NAND-flash SSDs are tuned for 4096-byte IOs. Matching the flash page size is unnecessary and ashift=12 is usually the correct choice. Public documentation on flash page size is also nearly non-existent. | |||
== ATA TRIM / SCSI UNMAP == | == ATA TRIM / SCSI UNMAP == |