Updating my own post iostat shows /dev/sdb is at 100% transferring at 4MB/S

So what limits a disk to 4MB/S???

On 18 March 2014 08:43, Jeff Allison jeff.allison@allygray.2y.net wrote:

OK todays problem.

I have a HP N54L Microserver running centos 6.5.

In this box I have a 3x2TB disk raid 5 array, which I am in the process of extending to a 4x2TB raid 5 array.

I've added the new disk --> mdadm --add /dev/md0 /dev/sdb

And grown the array --> mdadm --grow /dev/md0 --raid-devices=4

Now the problem the resync speed is v slow, it refuses to rise above 5MB, in general it sits at 4M.

from looking at glances it would appear that writing to the new disk is the bottle neck, /dev/sdb is the new disk.

Disk I/O In/s Out/s md0 0 0 sda1 0 0 sda2 0 1K sdb1 3.92M 0 sdc1 24.2M 54.7M sdd1 11.2M 54.7M sde1 16.3M 54.7M

I partitiioned the disk with --> parted -a optimal /dev/sdb

[root@nas ~]# parted -a optimal /dev/sdb GNU Parted 2.1 Using /dev/sdb Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: ATA ST2000DM001-1E61 (scsi) Disk /dev/sdb: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 2000GB 2000GB primary ntfs raid

There is no ntfs filesystem on the disk, I've still not worked out how to remove that flag.

I've followed the article here --> http://www.cyberciti.biz/tips/linux-raid-increase-resync-rebuild-speed.html to attempt to speed it up but no joy.

Any Ideas what I've done wrong?

parted output

[root@nas ~]# parted -l Model: ATA ST31000528AS (scsi) Disk /dev/sda: 1000GB Sector size (logical/physical): 512B/512B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 525MB 524MB primary ext4 boot 2 525MB 1000GB 1000GB primary lvm

Model: ATA ST2000DM001-1E61 (scsi) Disk /dev/sdb: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 2000GB 2000GB primary ntfs raid

Model: ATA ST2000DM001-9YN1 (scsi) Disk /dev/sdc: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 2000GB 2000GB primary raid

Model: ATA WDC WD25EZRS-00J (scsi) Disk /dev/sdd: 2500GB Sector size (logical/physical): 512B/4096B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 2000GB 2000GB primary ntfs raid

Model: ATA ST2000DL001-9VT1 (scsi) Disk /dev/sde: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: msdos

Number Start End Size Type File system Flags 1 1049kB 2000GB 2000GB primary raid