Do you want to proceed, possibly destroying your data? (Y/N) y
OK; writing new GPT partition table.

Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot.
The operation has completed successfully.

At this point i’ve rebooted to make the kernel use the new partition table & continued.

q@x:~$ sudo mkf
mkfifo mkfs mkfs.ext2 mkfs.ext4dev mkfs.ntfs
mkfontdir mkfs.bfs mkfs.ext3 mkfs.minix mkfs.vfat
mkfontscale mkfs.cramfs mkfs.ext4 mkfs.msdos
q@x:~$ sudo mkfs.ext4 /dev/md0p1
mke2fs 1.41.12 (17-May-2010)
/dev/md0p1 alignment is offset by 48128 bytes. <- still reported error.

This may result in very poor performance, (re)-partitioning suggested.
Filesystem label=
OS type: Linux

Once finished I formated & checked the array again and all was good again, weird no?

Glad it was helpful.

25MB/sec is actually about right for USB2. The 480mb per second speed of USB2 is megaBITS (same way networks speeds are measured, e.g. 100/1000mb ethernet), whereas your OS reports in megaBYTES. So the theoretical maximum of the bus itself is 60MB/sec, and this is shared between all USB devices on the system.

If you want better performance I’d recommend using eSATA drives.

Also the max speed I was able to get is 25MB/second.

the drives are brand new WD 2TB drives. 480mb/s usb speed supposedly.
What comes to mind to speed them up?

thank you again.

Thanks for that, I’ll add it to the article above.

For us really newbies the rest of the story would make us feel more comfortable. I added the ‘w’ at the end of the Command line and the resulting display and answers required to complete the partitioning action. I am using 10.04.

Command (? for help): w

Final checks completed. About to write GPT data. THIS WILL OVERWRITE EXISTING
MBR PARTITION!! THIS PROGRAM IS BETA QUALITY AT BEST. IF YOU LOSE ALL YOUR
DATA, YOU HAVE ONLY YOURSELF TO BLAME IF YOU ANSWER ‘Y’ BELOW!

Do you want to proceed, possibly destroying your data? (Y/N) Y
OK; writing new GPT table.
The operation has completed successfully

Other than that so far this is a great tutorial and guide. Now to finish the rest of the setup

Hey thanks Bruce, that link is very useful. I was under the misconception that WD Advanced Format drives actually presented 4K sectors, but ‘hdparm -I /dev/sdf’ confirms that this isn’t actually the case so my point about using GPT is moot. Partition alignment however will be critical.

Also need to finish the rest of this series, I’ve only just finished setting up the server itself!

You might also like this article about advances format drives:

http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/index.html?ca=drs-#gpt_solution