Capacity increase.

[Enquiries]

I have a DS1522+ with four 6TB drives in RAID5 (about 4 years of use). The system is now at 85% capacity (time to think about expanding).
I see two possibilities:
1. The obvious: a 6TB hd.
2. A larger hd (thinking of a future expansion).

I know that in both cases the gain in TB will be the same. But it seems to me that the second option is more advantageous in terms of future increase.
Am I right?

[ed]

You’re right to think about the bigger drive option for future-proofing. Here’s the deal:

Adding another 6TB drive will give you immediate extra space that matches your current drives, which is straightforward.

Adding a larger drive (e.g., 8TB or more) now won’t increase your usable capacity right away beyond what a 6TB would, since RAID5 limits the smallest drive size. But it does prepare you for future upgrades. When you replace your older 6TB drives with larger ones over time, your total capacity can grow without needing to replace all drives at once.

So yes, option two is generally more flexible and better for scaling your storage over the long term — you can start adding larger drives and expand gradually.

Just keep in mind that mixing drive sizes in RAID5 is supported but your usable space is limited by the smallest drive until you replace all drives with larger ones or migrate to a different RAID setup.

If you want maximum future growth, consider larger drives now. If you want a quick capacity boost and simplicity, matching your current drives is fine too.