Skip to content

Archive

SSD

14 articles
Tech 17 Sep 2026 9 min read

NVMe Queue Pairs Separate Command Submission from Completion

NVMe Queue Pairs Separate Command Submission from Completion An NVMe solid-state drive does not need the CPU to hand each storage command directly to a device register and then wait for that command to finish. Instead, NVMe places command and completion records in queues held in host memory. The controller reads pending commands from submission queues and writes results to associated completion queues. That arrangement matches fast PCIe storage well. Modern SSD controllers can process many operations at once across flash channels, internal dies, and controller pipelines. A queue model lets software keep that parallel hardware busy while avoiding a long series of synchronous command handoffs.

Tech 16 Sep 2026 5 min read

SSD TRIM Marks Unused Data for Controller Reclamation

Deleting a file changes filesystem metadata, but an SSD does not automatically know that every flash page formerly associated with the file can be treated as disposable. From the drive’s point of view, previously written logical block addresses can remain valid until the host explicitly indicates otherwise or overwrites them. TRIM provides that indication for ATA storage. Comparable deallocation commands exist in other storage protocols. The host identifies logical block ranges whose previous contents no longer need to be preserved, and the SSD can use that information when managing flash internally.

Tech 16 Sep 2026 5 min read

SSD Garbage Collection Amplifies Host Writes

An SSD can write substantially more data to NAND than the host sends to the device. The extra traffic appears when the controller must relocate still-valid pages before reclaiming flash blocks that contain invalid data. This internal movement is write amplification. It is a consequence of the mismatch between fine-grained logical updates and NAND erase constraints, not an extra write issued by the application. NAND pages cannot be overwritten in place NAND flash is programmed in pages but erased in larger erase blocks. A page that already contains programmed data cannot generally receive an arbitrary in-place replacement. The controller writes the new version to another available page and marks the old physical page as stale in its mapping state.

Tech 15 Sep 2026 5 min read

SSD Write Cache and Sustained Transfer Speed

An SSD can copy the first part of a large file at high speed, then settle at a much lower rate even though nothing else appears to have changed. That drop can be normal. Many consumer SSDs use part of their NAND as a fast write cache, allowing short bursts to finish before the drive has to sustain writes in its denser storage mode. This behavior makes a single peak transfer number a poor description of every write workload. Cache size, free space, NAND type, controller policy, temperature, and the amount of data already waiting inside the drive can all affect the speed seen during a long transfer.

Tech 15 Sep 2026 6 min read

SSD TRIM Marks Discarded Data for Flash Reuse

Deleting a file changes filesystem metadata, but that action does not automatically tell a solid-state drive which flash pages no longer contain useful data. From the drive’s point of view, previously written logical block addresses can remain valid until the host explicitly replaces them or marks them as discarded. TRIM closes that information gap. The operating system can notify the storage device that selected logical blocks no longer need their old contents. The SSD may then treat the associated data as disposable during its internal space-management work.

Tech 15 Sep 2026 7 min read

NVMe Queues Let Storage Handle Many Commands in Parallel

NVMe storage does not send every read or write through one shared command line. The protocol is built around queue pairs: software places commands into a submission queue, and the controller reports finished work through a corresponding completion queue. That structure matters most when several processor cores and application threads are generating storage work at the same time. Multiple queues can distribute command handling across cores, reduce contention around a single software path, and keep a fast solid-state drive supplied with enough outstanding work.

Tech 15 Sep 2026 6 min read

Flash Wear Leveling Spreads Erase Cycles Across NAND Cells

NAND flash has a finite endurance budget. Programming changes stored charge, but cells cannot simply overwrite arbitrary existing data in place. Pages are programmed inside larger erase blocks, and an erase operation resets a block before its pages can accept fresh programming. That geometry creates an endurance problem. A workload may update the same logical address thousands of times even though the drive contains many other blocks that receive almost no writes. If every logical address stayed permanently tied to one physical location, a small hot region could reach its erase-cycle limit while much of the flash remained lightly used.

Tech 14 Sep 2026 5 min read

SSD TRIM Marks Unused Blocks Before New Writes

Deleting a file changes filesystem metadata, but a solid-state drive cannot infer from that metadata alone which stored pages no longer contain useful data. Without an extra signal, the drive may continue treating those pages as valid even after the operating system has released their logical addresses. TRIM provides that signal. It lets the operating system tell the SSD that selected logical block addresses no longer hold data that must be preserved. The controller can then treat the corresponding flash pages as disposable during later maintenance and write preparation.

Tech 14 Sep 2026 6 min read

SSD TRIM Marks Deleted Blocks for Reuse

Deleting a file and erasing data from flash memory are separate events on a solid-state drive. A file system can mark storage as free without immediately forcing the SSD to erase the corresponding flash cells. TRIM connects those two layers. It lets the operating system tell the drive that selected logical block addresses no longer contain data the system needs to preserve. File deletion changes the host view first A file system keeps metadata that maps files to logical storage locations. When a file is deleted, the file system can release those locations for later use. From the operating system’s perspective, the space becomes available quickly.

Tech 14 Sep 2026 4 min read

NVMe APST Moves Idle SSDs Into Lower Power States

An NVMe SSD can support several power states rather than operating at one fixed power level. Active states favor quick access and throughput, while deeper idle states can reduce energy use at the cost of extra time needed to return to full activity. Autonomous Power State Transition, commonly shortened to APST, lets the host configure automatic movement into selected lower-power states after defined idle periods. Once configured, the controller can perform those transitions without a separate host command for every idle event.

Tech 13 Sep 2026 5 min read

SSD TRIM and Deleted Storage Blocks

Deleting a large file can make free space appear immediately in the operating system, yet the SSD underneath has a separate view of its flash memory. The file system knows that the file no longer occupies usable space. The drive, however, works through logical block addresses and does not infer file-system intent from a directory entry disappearing. TRIM bridges that gap. It allows host software to tell compatible storage that ranges of logical blocks no longer contain data the host needs. On NVMe storage, the comparable operation is commonly expressed through deallocation in the Dataset Management command. The practical result is similar: the controller can treat those logical ranges as unused when managing flash.

Tech 13 Sep 2026 7 min read

SSD TRIM and Deallocated Storage

Deleting a large file can make free space appear immediately in the operating system, yet an SSD does not treat that event like a hard drive overwriting a fixed physical location. The file system releases its own allocation first. A separate deallocation signal can then tell the SSD that the corresponding logical blocks no longer contain data the host needs. That signal is commonly called TRIM. On NVMe storage, the comparable operation is deallocation through Dataset Management. The names differ across storage interfaces, but the practical idea is similar: the host identifies logical ranges whose previous contents no longer need to be preserved.

Tech 12 Sep 2026 7 min read

SSD TRIM and Deleted Storage Space

Deleting a large file can make free space appear immediately in an operating system, yet the solid-state drive underneath may still contain the old data in flash cells for some time. The file system and the SSD are tracking different things. The file system knows which logical blocks are no longer needed; the drive manages where those blocks physically reside in flash. TRIM connects those two views. It lets an operating system tell an SSD that specified logical block addresses no longer contain data that must be preserved. The command does not act like a file shredder, and it does not directly erase every affected flash cell at the moment a file disappears.

Tech 02 Sep 2026 7 min read

SSD vs Hard Drive: What the Difference Means in Everyday Use

When choosing storage for a computer or an external drive, two common options are a solid-state drive (SSD) and a hard disk drive (HDD). Both can store operating systems, applications, photos, videos, documents, and backups, but they work in very different ways. For everyday use, the biggest differences are speed, physical durability, noise, power consumption, capacity, and cost. Understanding those trade-offs makes it easier to decide where each type of storage fits.