Solid state drives (SSDs) are a type of computer storage device that uses flash memory rather than spinning platters or discs. Unlike traditional hard disk drives (HDDs), SSDs have no moving parts and data is saved to non-volatile flash memory chips.
Fragmentation refers to the scattering of data in various locations across a storage device, rather than data being stored contiguously. When files are written and deleted over time, leftover pieces can get scattered throughout the drive, leading to fragmentation.
On traditional HDDs, fragmentation can slow down read/write speeds as the drive head spends more time seeking between the fragmented data. With SSDs, fragmentation works differently due to their lack of moving parts and different underlying technology. This article will examine how and why fragmentation occurs on SSDs, whether it impacts performance, and best practices for SSD maintenance.
How Fragmentation Occurs
Fragmentation occurs on traditional hard disk drives (HDDs) when files are not written sequentially. When a file is first saved to a hard drive, it is typically written in contiguous blocks. However, as files are modified and more data is added over time, the file may become fragmented across different physical locations on the disk platter. This happens because the hard drive writes data wherever there is available free space, which may not always be right next to the rest of the file’s data.
Defragmentation rearranges and consolidates these fragmented pieces of data so each file occupies contiguous physical blocks on the disk. This allows the hard drive’s read/write head to access the file without having to move around as much, improving performance. According to TechTarget, defragmentation can improve access times by up to 20% on heavily fragmented drives.
Do SSDs Get Fragmented?
SSDs can become fragmented in a similar way that traditional hard disk drives (HDDs) do. Fragmentation occurs when data is written to different areas of storage instead of contiguous blocks. Over time, as files are modified, deleted or moved, the free space on the drive becomes fragmented.
However, fragmentation is less of an issue for SSDs for a few key reasons:
SSDs have no moving parts and no physical “head” that needs to seek out fragmented data across the disk. Data can be accessed in parallel, so scattered data isn’t as much of a bottleneck. (Source)
SSDs perform something called garbage collection in the background to relocate data and rewrite it sequentially. This helps minimize performance impacts from fragmentation. (Source)
While an HDD may see significant slowdowns from fragmentation, SSD performance is generally less affected. The performance differences are often negligible for everyday computing tasks. (Source)
When Fragmentation Matters
Although SSDs are generally much less affected by fragmentation than traditional hard drives, there are some cases where fragmentation can impact SSD performance:
Very fragmented files with many non-contiguous pieces spread across the entire SSD can have slightly slower read speeds, as the drive head has to move around more to access all the fragments [1]. The impact is minor compared to a hard disk, but measurable.
When the free space on the SSD gets very low (under 10%), performance can degrade as it gets harder for the controller to find available blocks to write to. Defragmenting may help consolidate free space in this case [2].
On older SSDs without native TRIM support, manual defragmentation can help trigger garbage collection to free up unused blocks. Newer SSDs have continuous TRIM and do not need manual defrag.
Workloads with very demanding I/O requirements like big databases may see a minor benefit from defragmentation, but it’s not always recommended due to unnecessary write wear on the SSD.
In general, routine defragmentation is not necessary for SSDs. But in specific cases like critically low free space, it can provide a slight performance boost.
Detecting and Measuring Fragmentation
There are a few ways to analyze and measure fragmentation on an SSD:
On Windows, you can use the built-in Defragment and Optimize Drives utility to get a visualization of fragmentation levels. According to ZDNet, this tool shows “A simple graphical representation of the level of fragmentation” for SSDs[1].
Third-party tools like Auslogics Disk Defrag also provide fragmentation analysis and include an SSD optimization option. As noted by SuperUser users, Auslogics can detect fragmented files on an SSD and displays a numbered “Fragmentation Severity” rating[2].
For more in-depth analysis, the open source tool Fsutil can be used to run a query and output raw fragmentation data. According to tests on Overclock.net, running “fsutil volume querycluster [drive letter]” shows the number of fragmented and contiguous files on an SSD[3].
So in summary, while SSDs do not need defragmenting, Windows tools and third-party utilities can still detect and measure fragmentation levels on solid state drives.
[1] https://www.zdnet.com/article/windows-10-tip-defrag-secrets-for-hard-disks-and-ssds/
[2] https://superuser.com/questions/97071/do-ssds-get-fragmented-and-if-they-do-is-that-an-issue
[3] https://www.overclock.net/threads/yes-file-system-fragmentation-does-affect-ssd-read-speed.1538878/
Manual Defragmentation
Traditional hard disk drives (HDDs) can benefit from periodic defragmentation to optimize file storage and retrieval times. However, Solid State Drives (SSDs) function differently and do not require manual defragmentation. In fact, running defrag utilities on SSDs could negatively impact performance and longevity according to some experts.
Windows includes the native Defrag tool that can be used to defragment HDDs and SSDs. However, Microsoft recommends not manually running defrag on SSDs as it offers no benefit and can shorten the lifespan of the drive (Source). Third party utilities like Auslogics Disk Defrag also allow defragmenting SSDs, but this is not recommended by experts. Overall, manually defragmenting an SSD provides no performance boost and risks unnecessary wear on the drive.
TRIM and Garbage Collection
SSDs handle cleanup and optimization differently than traditional hard disk drives (HDDs). SSDs utilize features called TRIM and garbage collection to erase deleted data blocks and consolidate used blocks together for faster reads and writes.
When a file is deleted on an SSD, the operating system tells the SSD drive that the blocks containing that file are no longer needed via the TRIM command. This allows the SSD to mark those blocks as invalid and ready for erasure. The actual erasure doesn’t happen right away though.
SSD drives perform garbage collection periodically in the background to erase TRIM-marked blocks and rewrite any partially filled blocks to fully utilized blocks. This process helps free up storage space and optimize the SSD cells for continued fast performance. Garbage collection tends to impact write speeds more than read speeds.
The key point is that TRIM and garbage collection mean that deleted files and freed up space are not actually recoverable on SSDs. The data is permanently erased over time unlike HDDs where deleted content remains intact until being overwritten by new data. So fragmentation on SSDs does not affect recoverability like it can on traditional hard drives.
For sources see:
https://www.officer.com/investigations/forensics/digital-forensics/article/21282421/belkasoft-even-5-more-bloopers-of-a-digital-forensic-investigator-part-3
https://vapefi.com/data-acquisition-with-the-absence-of-a-write-blocker
Recommended Best Practices
Since SSDs don’t benefit from defragmentation in the same way traditional HDDs do, the recommended best practices for minimizing fragmentation issues are different:
– Enable TRIM support if your operating system and SSD support it. TRIM allows the SSD to more efficiently perform garbage collection and clearing of invalid pages. This helps maintain performance over time.[1]
– Maintain at least 10-20% free space on the SSD. Having ample free space allows garbage collection to work more efficiently.[2]
– Periodically secure erase the SSD to reset all cells to an empty state. Many SSD manufacturers recommend doing this every 6-12 months.[1]
– Update SSD firmware when new versions are available, as they often include improvements to garbage collection algorithms.
– Use a modern operating system optimized for SSDs, such as Windows 10 or Linux kernels 3.7 and above.
– Minimize unnecessary writes to the SSD from temporary files, caches, etc.
– Migrate data off the SSD that doesn’t benefit from the speed, like archival photos or videos.
[1]https://www.crucial.com/articles/about-ssd/should-you-defrag-an-ssd
[2]https://www.adldata.org/wp-content/uploads/2015/06/Best_Practices_Eliminating_Fragmentation.pdf
The Bottom Line
In summary, SSDs do technically get fragmented at the file system level, but it does not significantly impact performance or endurance the way defragmentation does for traditional hard disk drives. This is due to the fundamental differences in how SSDs access data compared to HDDs. Specifically, SSDs do not have to physically seek out fragmented data sectors spread across platters like HDDs. Rather, SSDs can access any data location instantly and in parallel. While some test benchmarks have shown minor improvements from defragmenting SSDs, most experts agree it is an unnecessary process that wastes drive writes. The built-in TRIM and garbage collection routines are usually sufficient to maintain performance over time. The best practices are to leave TRIM enabled, minimize unnecessary drive writes, and avoid manually defragmenting SSDs unless you actually notice degraded performance over time.
References
Crucial. “Should You Defrag an SSD?” Crucial.com, Micron Technology, Inc., https://www.crucial.com/articles/about-ssd/should-you-defrag-an-ssd. Accessed [date accessed].
Condusiv Technologies. “Everything You Need to Know about SSDs and Fragmentation in 5 Minutes.” Condusiv.com, Condusiv Technologies, 4 Apr. 2022, https://condusiv.com/everything-you-need-to-know-about-ssds-and-fragmentation-in-5-minutes/. Accessed [date accessed].
“Do SSDs get fragmented, and if they do, is that an issue?” SuperUser, Stack Exchange, 17 Jan. 2010, https://superuser.com/questions/97071/do-ssds-get-fragmented-and-if-they-do-is-that-an-issue. Accessed [date accessed].