![]() Many versions fstrim shipped with earlier releases of Ubuntu do not contain this option.įor other systemd distributions, periodic TRIM can be enabled with the fstrim.timer file, which will run TRIM operations on all capable, mounted drives once a week. # trim all mounted file systems which support itĪs you can see, this script needs a version of fstrim with the -all flag. ![]() Before we enable periodic TRIM, it makes sense to take a look at our current mount options.Ĭontinuous TRIM is enabled by mounting a drive or partition with the discard option.įirst, find the filesystems that are currently mounted with the discard option: You may have already enabled continuous TRIM on your devices when they were mounted. Configuring periodic TRIM gives the device bulk information about unneeded pages on a regular schedule instead of with each operation. Performing TRIM on every deletion can be costly however and can have a negative impact on the performance of the drive. The SSD can shuffle data ahead of time, clean up stale pages, and generally keep the device in good working condition. This allows the device to perform its regular garbage collecting duties when idle, in order to ensure that there are zeroed pages ready to handle new writes. The TRIM command propagates information about which data is no longer being used from the filesystem down to the SSD. It cannot perform its garbage collection routines because it is never informed when data is deleted, just when the space previously reserved for it should now be used for other data. This means that the SSD will typically not know that a page is no longer needed until it receives instructions from the filesystem to write to the same logical location at a later time. They do not actually erase the data from the underlying storage, but may overwrite the area previously occupied by that data on subsequent writes. However, filesystems typically "delete" data by just marking it in their own records as space that is available again. The SSD's internal garbage collecting processes are responsible for erasing blocks and managing wear leveling. The old block, which now contains no unique, still-in-use data can then be zeroed and marked as ready for future writes. Again, the internal table mapping logical and physical locations is updated. To reclaim the stale pages, the SSD's internal garbage collecting processes must read all of the valid pages from a block and write them to a new block. The old location is marked in a different internal table as stale: not in use, but not yet zeroed. It then updates an internal table to map the logical location that the operating system is given to the new physical location of the data on the device. To modify data, the SSD actually has to read the information from the old location, modify it in memory, and then write the modified data to new, zeroed pages. This means that overwriting data directly is impossible. Another limitation is that writes can only be performed on pages that have been completely zeroed (all bits set to 0). However, they can only erase data at the block level. SSDs can read and write to pages individually. Pages, in turn, are grouped together in larger units called blocks. To better understand the problems that TRIM solves, it helps to know a few things about how SSDs store and manage their data.ĭata on SSDs is written and read in units of a fixed size known as pages. ![]() In this guide, we will briefly discuss how SSDs and TRIM work and then demonstrate how to enable periodic TRIM on a variety of Linux distributions. In almost all cases it provides the same benefits of continuous TRIM without the performance hit. This configures the operating system to TRIM the drive on a schedule instead of as a necessary component of regular file operations. A gentler alternative is to configure periodic TRIM. While it is possible to enable continuous TRIM in Linux, this can actually negatively affect performance because of the additional overhead on normal file operations. TRIM can have a major impact on the device's performance over time and its overall longevity. This allows the SSD's internal systems to better manage wear leveling and prepare the device for future writes. The TRIM command is an operation that allows the operating system to propagate information down to the SSD about which blocks of data are no longer in use. Due to the architecture of SSDs, or solid state drives, continuous use results in degraded performance if not accounted for and mitigated. ![]()
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