Hyphenation of well-known compound nouns used adjectivally [duplicate]

This is a very good question and is one that troubled me for a long time.

Here is what the Fowler brothers say in their Kings English:

TEXT 1: Within the last ten days two Anglo-South Americans have been in my office arranging for passages to New Zealand.—Times.

SUGGESTION 1: Anglo-South-Americans is the best that can be done. What is really wanted is Anglo-SouthAmericans, to show that South goes more closely with America. But it is too hopelessly contrary to usage at present.

TEXT 2: The proceeds of the recent London-New York loan.—Times.

SUGGESTION 2: London and New-York loan.

TEXT 3: A good, generous, King Mark-like sort of man.—Times.

SUGGESTION 3: King-Mark-like, in default of KingMark-like. But the addition of -like to compound names should be avoided.

TEXT 4: The Fugitive Slave-law in America before the rebellion.—H. Sidgwick.

SUGGESTION 4: Fugitive-Slave law

In answer to your question, based on Fowler's advice (which I find practical and logical), I would write filesystem-related or file-system-related, e.g., 'Please remember that this is a filesystem-related job.'

You're looking at a compound compound modifier.

Generally, a compound modifier (a two-word phrase that is used as an adjective) is hyphenated when it appears before the noun it is modifying:

• The brick-oven pizza was cooked in a brick oven.
• Love is a two-way street.

The hyphen is there to prevent confusion on which words are being modified. There may be more important reasons, but this is the more-important reason.

Each of the components of a compound adjective can itself be a compound word. It is common in this case to use an "en dash" to keep things well organized:

• I plan to open a brick-oven–pizza restaurant.
• All file-system–related software has to be cleared by IT.