Depolama alanı yeterli olduğu halde raf ünitesi yerleştirilemedi.

Because depolama alanı is a Turkish noun compound, meaning storage area / storage space.

In this kind of compound, the second noun usually takes the 3rd person possessive ending:

• depolama = storage
• alan = area, space
• alanı = the compound form used after another noun

So:

• depolama alanı = storage space
• similar patterns:
  • yemek masası = dining table
  • otobüs durağı = bus stop
  • kitap kapağı = book cover

That -ı here does not mean the area as a direct object. It is just part of the compound structure.

For the same reason: raf ünitesi is also a noun compound.

• raf = shelf
• ünite = unit
• ünitesi = shelf unit / shelving unit

The -si on ünite is the normal compound ending after a vowel-final noun.

So both noun phrases in the sentence use the same pattern:

• depolama alanı = storage space
• raf ünitesi = shelf unit

Olduğu halde means although, even though, or despite the fact that.

In this sentence:

• Depolama alanı yeterli olduğu halde = Although the storage space was sufficient

A very literal way to think about it is something like:

• olduğu = being / the fact that it is-was
• halde = in the state/condition of

Together, they form a common concessive expression showing contrast:

• X olduğu halde, Y = Although X, Y

So the sentence sets up a contrast:

• there was enough space,
• but the shelf unit still could not be placed.

Olduğu comes from olmak = to be / to become.

Here it is a subordinate-clause form of the verb, used before halde. You do not need to translate it word-for-word every time, but it helps to know what it is doing:

• yeterli = sufficient
• yeterli olduğu = that it was sufficient / being sufficient
• yeterli olduğu halde = although it was sufficient

So olduğu is the piece that supplies the idea of was / being in the clause.

English usually just says although it was enough/sufficient, but Turkish often uses this kind of verbal form inside longer structures.

Yerleştirilemedi breaks down like this:

• yerleştir- = place, install, position
• -il- = passive
• -e- = ability/potential in its shortened negative form
• -me- = negation
• -di = past tense

So:

• yerleştirilemedi = could not be placed / could not be installed

This is important:

• yerleştirilmedi = was not placed
• yerleştirilemedi = could not be placed

The extra -e- changes the meaning from simple non-occurrence to inability / impossibility.

Yes, the main clause is passive.

Main clause:

• raf ünitesi yerleştirilemedi = the shelf unit could not be placed

Here, raf ünitesi is the grammatical subject of the passive sentence.

In an active version, you would need someone doing the action, for example:

• Birisi raf ünitesini yerleştiremedi.
• Someone could not place the shelf unit.

But in the original sentence, the actor is not mentioned. The focus is on the result: the shelf unit could not be placed.

Because Turkish often expresses this idea more directly than English does.

English often says:

• There was enough storage space

Turkish can simply describe the noun with an adjective:

• Depolama alanı yeterli = The storage space is/was sufficient

Then in a subordinate clause, olduğu helps carry the was/being meaning:

• Depolama alanı yeterli olduğu halde = Although the storage space was sufficient

So Turkish does not need an exact equivalent of English there was here.

Because Turkish very often puts the context or background information before the main result.

So the structure is:

• Depolama alanı yeterli olduğu halde = background/contrast
• raf ünitesi yerleştirilemedi = main point

This is very natural in Turkish. It is similar to English:

• Although there was enough storage space, the shelf unit could not be placed.

You could also move things around somewhat, for example:

• Raf ünitesi, depolama alanı yeterli olduğu halde, yerleştirilemedi.

But the original version is smooth and typical.

Yes. Turkish has several ways to express although / even though / despite.

Possible alternatives include:

• Depolama alanı yeterli olmasına rağmen raf ünitesi yerleştirilemedi.
• Depolama alanı yeterli olsa da raf ünitesi yerleştirilemedi.

These are all close in meaning, but there are small differences in tone:

• olduğu halde = common, neutral
• olmasına rağmen = a bit more formal/written
• olsa da = also common; can feel slightly lighter or more conversational depending on context

All of them express contrast.

It usually suggests an unsuccessful attempt or inability, not just that the action did not happen.

So this sentence implies something like:

• there was enough storage space,
• but for some reason the shelf unit still could not be placed/installed.

That reason might be size, shape, layout, access, design, or some other obstacle.

If you only wanted to say it was not placed, without the idea of inability, Turkish would more likely use:

• yerleştirilmedi = it was not placed

So yerleştirilemedi adds the nuance of could not.