Hi,
first I have to confess I am quite an amateur with Linux, however I try to get things done using thousands of Google searches to achieve that.

But I am running in some problems now with my RAID.

Let me explain the system itself first, as it is probably quite unusual:

It is a home data center, and I was cheap when buying it as any professional solution with that much space would cost me 3 times more and since I don't need enterprise-grade QoS at home, I didn't see any point in spending that much money.

System:
SOHO PC with AMD 8320 8 core cpu, GA-970A-DS3P, 16GB DDR3 1600MHz
Win Server 2012; Hyper-V

I have disks (connected through 2 Hyper-V SCSI controllers):
- 3*WD30EZRX (3TB)
- 1*WD20EARX (2TB)
- 1*WD20EARS (2TB)
- 2*Samsung D3 station USB 3.0 (3TB)

3TB drives are formattet to 2TB and 1TB partitions.

Together they form a 12TiB RAID 5 (7*2TB partition) and a 3TiB RAID 6 (5*1TB partition), both ext4 formatted.

My first problem is the speed, writing to RAID 5 achieves from 10 do 15MB/s, for comparison rebuilding goes up to 60MB/s. However I'd expect at least the speed of slowest drive (the 2TB WD; cca. 130MB/s). So, what can be wrong?

The other problem is, since I am used to Windows permissions delegation, I shared Raid 5 and Raid 6 only with the Win Server, on each of them there is a vhdx file, which is mounted on Win Server. However when I perform some massive writes to RAID, the Samba shared mapped drive goes offline from time to time for a few seconds, which is highly inconvenient since it dismounts my vhdx. Any idea why this happens? Maybe I should try sharing files directly from Linux? Is there any nice GUI solution to connect to ActiveDirectory and define permissions for every single directory in Samba?

Hi Derbin,

Is your switch a Gbit? 10/15MB sounds like your running on 100Mbps hardware.

My guess on the second one is your USB chip can't handle the through put for that long, (cheap controller)

Hi,
thanks for you reply, but unfortunately it doesn't solve my problems. I do gave a Gb network, and I can write at 100-115MB/s to RAID as long as Windows server doesn't run out of ram (it caches writes to the vhdx), so that's not the case.

About outages I forgot to say that usually just one raid goes offline at a time, so I lose only one vhdx mount (or maybe Windows just doesn't notice it on the idle vhdx). However I have experienced a momentary controller freeze, which resulted in a missing drive in RAID, so I guess in the controller was falling down, I would have to reassemble RAID every time that would happen. I have also blamed usb controller for low transfer speeds, so I installed a PCIe controller which gave me the same speeds - by the way R/W speeds of these USB disks are about 170/150MB/s

So, any other idea maybe? :-O