What does COW stand for?
| Full form | Copy-on-Write |
|---|---|
| Category | Technology & computing |
| Type | Abbreviation |
The abbreviation COW stands for Copy-on-Write in computing. In the memory-management example described here, processes can share a page until a write requires a private copy for the process making the change.
This guide uses process memory to explain the idea. COW is also used in storage systems such as Btrfs, whose implementation details differ. A shared read does not itself mean that a private copy has already been made, and this exercise does not measure memory usage.
Meaning in context
- Copy
- A private copy is associated with the writing process rather than being assumed at every read.
- on Write
- The attempted modification is the important event in this memory-sharing example.
Practical examples
Explain a read
- Before
Both processes read the page, so both immediately receive private copies.
- After
Both processes can read the shared page; a later write can require a private copy for the writing process.
The revision keeps reading and modification separate instead of treating every access as a copy.
Explain isolation
- Before
The child changes its private COW page, so the parent's value must change too.
- After
The child writes to its private copy; the parent can retain the original value.
The point of the private copy is that the writing process can modify its data without treating the change as a write to the other process's page.
Original illustrative examples, not quotations or reports of actual events.
Use COW with clarity
Which event in a COW explanation causes a private copy?
See all guidance
Both processes read
In this example, shared reading does not require a write-triggered private copy.
Parent and child read the shared original.
One process writes
Identify the writer and describe its private copy.
The child modifies its private copy.
Explain the limitation
A conceptual description does not establish exact copying costs or memory totals.
We need a measurement to establish the workload's actual memory usage.
These are illustrative exercises. The tool prepares a draft in your browser; it does not inspect your system, change settings or confirm the facts you enter.
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By AcronymIndex Editorial Team · Editorial policy