I just upgraded and reinstalled my home server. One thing I did was going from software raid to a raid card.
After doing this and starting to copy back my backups, I've noticed that my first ~1TB backup takes up ~1.4TB of space on my new array. Since thats a whopping 400GB increase in space used, I'm guessing I've done something wrong.
I have my OS installed on a separate 32GB SSD. All drives used in the array are WD Red 2TB WD20EFRX.
My old setup was on Ubuntu 14.04 Desktop with a 3x2TB RAID-5 array (leaving 4TB available). I was using the software raid function in my motherboards BIOS. I had partitioned and formated the array using the Disk Utility in GNOME. I'm not sure what format I used. It was most likely what was presented as default for me.
My new setup is on Ubuntu 14.10 Server. The array is now a 6x2TB RAID-5 array (leaving 10TB available in theory). I'm now using the RocketRaid 2720SGL "fake hardware" raid card.
I installed the driver and WebGUI and then initialised the drives and created the new RAID-5 array through the RocketRaid WebGUI (which I read in reviews was strongly recommended over the cards BIOS function). Being unsure on the more advanced settings, I picked the default sector size of 512B. The build process ran through the night successfully.
Using fdisk I then partitioned the array. Due to the size of the disk fdisk warned me that I needed to select the GUID partition table - which I did. I formated the array as ext4 (seemed the recommended choice from my research). For sector size, sector start and sector end I picked the default values presented to me.
Using fdisk -l it looks like this right now
Device Start End Sectors Size Type /dev/sdb1 2048 19534315486 19534313439 9.1T Linux filesystem
I initially looked at picking 4K instead of 512B when building the array. However when I researched the drives I use I found some debate concerning getting 4K sector size to work on them, so I decided against it.
I had my original array backed up on 3 different external 1TB drives. I had copied ~980GB chunk of directories from the original array to the first external drive (the external drive is formated as ext4). Restoring from this external drive I connected the drive via USB to the server and mounted it to /media/usb. I then used this command to copy the backup from the first external drive to my new array.
rsync -av /media/usb /media/array/drive-one
This copied everything on the external drive (should be 980GB). These files are now taking up 1.38TB on my new array.
So, could it have anything to do how I configured the sectors? Or perhaps the way I'm copying the files from my backup?