Tag Archive for 'nas'

Live migrating Btrfs from RAID 5/6 to RAID 10

Recently it was discovered that the RAID 5/6 implementation in Btrfs is broken, due to the fact that can miscalculate parity (which is rather important in RAID 5 and RAID 6).

So what to do with an existing setup that’s running native Btfs RAID 5/6?

Well, fortunately, this issue doesn’t affect non-parity based RAID levels such as 1 and 0 (and combinations thereof) and it also doesn’t affect a Btrfs filesystem that’s sitting on top of a standard Linux Software RAID (md) device.

So if down-time isn’t a problem, we could re-create the RAID 5/6 array using md and put Btrfs back on top and restore our data… or, thanks to Btrfs itself, we can live migrate it to RAID 10!

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Building a Mini-ITX NAS? Don’t buy a Silverstone DS380 case.

Edit: I made some changes which have dropped the temps to around 40 degrees at idle (haven’t tested at load yet). The case has potential, but I still think it’s slightly too cramped and the airflow is not good enough.

Here’s what I changed:

  • Rearranged the drives to leave a gap between each one, which basically limits the unit to 4 drives instead of 8
  • Inverted the PSU as per suggestion from Dan, so that it helps to draw air through the case. The default for the PSU is to draw air from outside and bypass the case.
  • Plugged the rear and side fans directly into the PSU molex connector, rather than through mainboard and rear of hard drive chassis

So I’m building a NAS (running Fedora Server) and thought that the Silverstone DS380 case looked great. It has 8 hot-swappable SATA bays, claims decent cooling with filters, neat form factor.


It requires an SFX PSU, but there are some that have enough juice on the 12v rail (although avoid the SilverStone SX500-LG, it’s slightly too long) so that it’s not a major problem (although I would prefer standard ATX).

So I got one to run low-power i3, C226 chipset mainboard and five HGST 3TB NAS drives. Unfortunately the cooling through the drives is pretty much non-existent. The two fans on the side draw air in but blow onto the hotswap chassis and nothing really draws air through it.

As a result, many of the drives run around 65 degrees Celsius at idle (tested overnight) which is already outside of the drives’ recommended temperature range of 0-60 degrees.

I’ve replaced the case with my second choice Fractal Design NODE 304 and the drives at idle all sit at around 35 degrees.


It has two smaller fans at the front to bring air directly over the drives and a larger one at the rear, with a manual L/M/H speed controller for all three on the rear of the case. As a bonus, it uses a standard ATX power supply and has plenty of room for it.

The only downside I’ve found so far is the lack of hot-swap, but my NAS isn’t mission-critical so that’s not a deal breaker for me.

Your mileage might vary, but I won’t buy the DS380 for a NAS again, unless it’s going to run full of SSDs or something (or I heavily mod the case). It’s OK for a small machine though without a bunch of disks (shame!) and that’s what I’ve re-purposed it for now.