HowTo: Recover RAID volume and mount seperatly

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My NAS storage was crashed, this time I was forced to move one of the raid volume to another server to make the service up because the volume contains all VM’s used by XEN server,  most probably  it is a LVM disk.

Everybody knows that we can’t simply attach the raid disk to another machine, so just follow the procedures below.

Once I attached the HDD to another machine. check the disk availability

root@ubuntu:~# mdadm --examine /dev/sdb
 Magic : a92b4efc
 Version : 1.2
 Feature Map : 0x0
 Array UUID : ec2c6fb2:f211cfa5:8dfa8777:4f08bfed
 Name : openmediavault:storage
 Creation Time : Fri May 9 16:22:45 2014
 Raid Level : raid1
 Raid Devices : 2
Avail Dev Size : 1953523120 (931.51 GiB 1000.20 GB)
 Array Size : 976761424 (931.51 GiB 1000.20 GB)
 Used Dev Size : 1953522848 (931.51 GiB 1000.20 GB)
 Data Offset : 2048 sectors
 Super Offset : 8 sectors
 State : clean
 Device UUID : 3a9e90a0:ca0e458e:c48e1b34:f3aaf06f
Update Time : Tue Jun 24 16:20:00 2014
 Checksum : eaa54b02 - correct
 Events : 24468
 Device Role : Active device 1
 Array State : .A ('A' == active, '.' == missing)

It sounds good now move to the next step, It should be create the block device md* so it will be reveal the partitions.

root@ubuntu:~# mdadm --assemble --force /dev/md127 /dev/sdb

You will get the output like this

root@ubuntu:~# ll  /dev/md127
 brw-rw---- 1 root disk 9, 127 Jun 24 14:27 /dev/md127

Now you can see the LVM names

root@ubuntu:~# lvs
 LV   VG      Attr   LSize   Origin Snap%  Move Log Copy%  Convert
 nfs  storage -wi-ao 931.51g
 root@ubuntu:~# pvs
 PV         VG      Fmt  Attr PSize   PFree
 /dev/md127 storage lvm2 a-   931.51g    0
 root@ubuntu:~# vgs
 VG      #PV #LV #SN Attr   VSize   VFree
 storage   1   1   0 wz--n- 931.51g    0

Mount the partition manually

root@ubuntu:~# mount /dev/mapper/storage-nfs /export/
root@ubuntu:~# mount | grep nfs
 /dev/mapper/storage-nfs on /export type ext4 (rw)

That’s it now I got my files back,






Info: Linux I/O Performance Tests For HDD ageing calculation

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Hard Disk Data Transfer Speed measuring technique

How do you find out how fast is your hard disk under Linux? Is it running at SATA I (150 MB/s) or SATA II (300 MB/s) speed without opening computer case or chassis?

hdparm -tT /dev/sda
 Timing cached reads:   19884 MB in  2.00 seconds = 9954.83 MB/sec
 Timing buffered disk reads: 276 MB in  3.00 seconds =  91.88 MB/sec

To find HDD supported speed

hdparm -I /dev/sda | grep -i speed


       *    Gen1 signaling speed (1.5Gb/s)
       *    Gen2 signaling speed (3.0Gb/s)
       *    Gen3 signaling speed (6.0Gb/s)

Similarly you can use the dd command as follows to get speed info too:

Disk speed indicative of performance, different test different things,  on virtual environments (such as OpenVZ and KVM) and dedi, some tests might be better for some of them.

You can use the dd command as follows to get speed info too:

dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync 
16384+0 records in 
16384+0 records out 
1073741824 bytes (1.1 GB) copied, 24.6998 s, 43.5 MB/

How to judge your result (note that this is only accurate for the exact test above)

  • 0-25 MB/s -> Garbage
  • 25-70 MB/s -> Acceptable
  • 70-120 MB/s -> Good
  • >120 MB/s -> Excellent

Howto: Installing 3Ware tw_cli RAID monitoring software utility

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3ware CLI is a command line interface for managing 3ware RAID Controllers. We can use the CLI to view unit status and version information and perform maintenance functions such as adding or removing drives. 3ware CLI also includes advanced features for creating and deleting RAID units online.

More useful commands here:

The 3ware CLI is supported under the following operating systems:
• Mac OS X 10.4.6 or later, running in a Mac Pro or Power Mac® G5
(PowerPC-based) with PCI Express®
• Windows®. Windows 2000, Windows XP, and Windows Server 2003,
both 32-bit and 64-bit.
• Linux®. Redhat, SuSE, both 32-bit and 64-bit.
• FreeBSD®, both 32-bit and 64-bit.

Installation steps

root@drupaldedicated:~# vi /etc/apt/sources.list

Add the following lines in end of the line

# 3Ware

deb lenny restricted

root@drupaldedicated:~# wget -O - | apt-key add -
root@drupaldedicated:~# apt-get update
root@drupaldedicated:~# apt-cache search 3ware
root@drupaldedicated:~# aptitude install 3ware-3dm2-binary 3ware-cli-binary 
root@drupaldedicated:~# cd /etc/3dm2 
root@drupaldedicated:~# cp 3dm2.conf 3dm2.conf-dist
root@drupaldedicated:~# vi 3dm2.conf

Edit 3dm2.conf

set :  RemoteAccess 1

root@drupaldedicated:~# /etc/init.d/3dm2 restart

Browse to https://yourhost:888/
Select 3DM 2 Settings and change the default password 3ware to something secure. If you lock yourself out, you can copy the original config file back in place as it has the default password.

To initial checking RAID drives use the below commands.

root@drupaldedicated:~# tw_cli info


Ctl   Model        (V)Ports  Drives   Units   NotOpt  RRate   VRate  BBU
c0    8006-2LP     2         2        1       0       3       -      -   
root@drupaldedicated:~# tw_cli info

Output :

Unit  UnitType  Status         %RCmpl  %V/I/M  Stripe  Size(GB)  Cache  AVrfy
u0    RAID-1    OK             -       -       -       465.761   OFF    -      

Port   Status           Unit   Size        Blocks        Serial
p0     OK               u0     465.76 GB   976773168     WD-WMAYUE464012     
p1     OK               u0     465.76 GB   976773168     WD-WMAYUE397313

Type the following command to view smart information about the hard disk behind 3Ware RAID card, enter:

root@drupaldedicated:~# smartctl -a -d 3ware,0 /dev/twa0
root@drupaldedicated:~# smartctl -a -d 3ware,1 /dev/twa0