The cell endurance varies with used technology. Įach write operation performed on a NAND flash cell causes its wear. There are two basic approaches to issue the discard command - using mount discard option ( -o discard) for continuous discard or periodic calls of fstrim utility. Also there are filesystems developed primarily for flash-based devices, such as F2FS. Majority of modern filesystems (like Ext4, XFS or Btrfs ) support discard. Filesystem's support is required in order to use discard. Names of implementations differ - TRIM for ATAPI and UNMAP for SCSI. The described mechanism is called discard. This problem is further amplified by hardware limitations.įor modern kernels it is possible to hint the deleted (not-used) data blocks to SSD. Thus writing to physically non-empty cells, flagged as deleted by a filesystem, requires their erasure which makes the operation slower than writing to empty cells. Due to nature of flash memory cells any write operation has to be done to empty cells only. Generally, traditional filesystems do not erase deleted data blocks but only flags them as such. However, the flash-based technology brings a few issues which require some special system attention and care. Compared to conventional HDD, flash-based technology offers a much faster access time, lower latency, silent operation, power savings (no moving parts), and more. The term Solid State Drive is commonly used for flash-based block devices. 4.2.4 Web browser profile(s) and cache on tmpfs.4.1.5 Without cron, on system shutdown (with OpenRC).3.2.1.1 List of devices with known erase block sizes.
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