Reflink
Reflinks (also Refer-Link or Referral-Link, from English to refer = German to refer) has several meanings.
On the one hand, it describes hyperlinks that refer to an often commercial page, on the other hand, it can also refer to file links in file systems.
Use in online marketing
They are widely used in online marketing . By clicking on a reference link, the operator of this link can determine how many clicks were generated. This is useful, for example, when soliciting friends over the Internet. Reflinks can be found relatively easily using the URL . In most cases, this is the identification number or name of the advertiser.
The difference to a normal link is that a re-link is always useful for the person behind the re-link, while a normal link is a simple reference.
From a technical point of view, it is also a parameter transfer within the URL .
Use in file systems
Several Linux file systems (including btrfs , xfs ) have a feature called reflinks. When copying files with reflinks, extents and copy-on-write create a quick copy of the data by simply adding another reference to the extents that are currently using the data, rather than having to read and write all the data back like it would be the case in other file systems.
Without reflinks, a common technique for making a quick copy of a file is to use the hardlink . However, hardlinks have a number of disadvantages, especially since there is only one inode , all hardlinked copies must have the same metadata (owner, group, permissions etc.). Software that could change the files must also watch out for hard links: a naive change to a hardlinked file changes all copies of the file.