Apparently quite some people were anticipating the FW 3.2.5 because of the support for WD's advanced format technology using 4k sectors. Same for me: I have two WD15EARS disks in a TS-219P.
Up to now I was using FW 3.2.4, but with a little knowledge in Linux and mdadm I had manually repartitioned the drives (using fdisk -H 224 -S 56 /dev/sda in my Linux machine and manually re-added them with mdadm) so the partitions should have been alingned to 4k sectors.
Performance was around 20..25MB/s on SMB-write, IIRC. Not the world, but good enough for me.
This week I was upgrading to the FW 3.2.5 because of its native support for 4k alignment.
For a complete reinstall I have used the method of removing all disks on powering up, as described in the QNAP Wiki. It must have worked, since everything came up as expected. The new FW had also repartitioned the drives. Good.
Writing with 12 MByte/s via SMB it seems way too slow.
On the NAS, top showd smbd to always consume <50% of the CPU.
What makes me worry:
Investigating the new partition layout, I was curious why it still uses the old 255 heads, 63 sectors/track geometry, which just calls for a misalignment of the partitions. Because 16065 sectors (255*63) is a quite inconvenient number of sectors per clinder, if we want to generate partitions with a beginning aligned to 4k (i.e. sector number divisible by 8 ).
Here's how FW 3.2.5 partitioned my WD drives, shown by sectors:
Code: Select all
[~] # fdisk -ul /dev/sda
Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 63 1060289 530113+ 83 Linux
/dev/sda2 1060290 2120579 530145 82 Linux swap / Solaris
/dev/sda3 2120580 2929259969 1463569695 83 Linux
/dev/sda4 2929259970 2930255999 498015 83 Linux
If we take a look at the sector numbers in the Start column, we find that none of these is divisible by 8.
the partitions 3 (the actual data volume) seems to be 2k (4 sect) off the optimum alignment.
To my knowledge, adding the the md device (in RAID-1) does not shift the start of the actual filesystem, since the md-superblocks are stored at the end of each partition.
This offset would lead to the performance degaration found by many.
Finally, here's the question(s):
How did QNAP implement the support for 4k sectors?
And how can I check if it is actually used correctly?
I'd appreciate If someone can enlighten me how to find this out...
Or support in testing where possible.