Solved

Linux device disks

Posted on 2015-02-06
6
187 Views
Last Modified: 2015-03-18
We were just checking a linux server  that currently has a 4 physical disk drives and one of them  failed. The following are outputs for the system.  We dont' know Linux. Could someone explain the outputs. Like for instance: what is md1 and are sdb3 and sda3  the physical disks or partitions of a physical disk.
-----------------------------------------------------------
[root@r101s0u1bak ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md5 : active raid0 md3[0] md4[1]
      3802994752 blocks 64k chunks

md1 : active raid1 sdb3[1] sda3[0]
      8008320 blocks [2/2] [UU]

md3 : active raid1 sdb5[1] sda5[0]
      1899493312 blocks [2/2] [UU]

md2 : active raid1 sdc1[1]
      50010176 blocks [2/1] [_U]

md4 : active raid1 sdc2[1]
      1903501568 blocks [2/1] [_U]

md0 : active raid1 sdb2[1] sda2[0]
      45761088 blocks [2/2] [UU]
----------------------------------------------------

[root@r101s0u1bak ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/md0               43G  4.0G   37G  10% /
/dev/md2               47G  625M   44G   2% /usr/bp
/dev/sdb1             236M   18M  206M   8% /mnt/boot_sync
/dev/sda1             236M   18M  206M   8% /boot
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/md5              3.6T  1.6T  2.0T  44% /backups
[root@r101s0u1bak ~]#
0
Comment
Question by:Shen
  • 3
  • 2
6 Comments
 
LVL 84

Assisted Solution

by:ozo
ozo earned 500 total points
ID: 40593602
md5 : active raid0 md3[0] md4[1]
      3802994752 blocks 64k chunks
/dev/md5 is an active, raid0 array  with component devices  /dev/md3 [device 0] and /dev/md4 [device 1]

md1 : active raid1 sdb3[1] sda3[0]
      8008320 blocks [2/2] [UU]
/dev/md1 is an active, raid1 array with component devices /dev/sdb3 [device 1] and  /dev/sda3  [device 0]
out of 2 devices, 2 are in use, and both are Up

md3 : active raid1 sdb5[1] sda5[0]
      1899493312 blocks [2/2] [UU]
/dev/md3 is an active, raid1 array with component devices /dev/sdb5 [device 1] and  /dev/sda5  [device 0]
out of 2 devices, 2 are in use, and both are Up

md2 : active raid1 sdc1[1]
      50010176 blocks [2/1] [_U]
/dev/md2 is an active, raid1 array with component device /dev/sdc1 [device 1]
out of 2 devices, 1 is in in use, device 0 is down and device 1 is up

md4 : active raid1 sdc2[1]
      1903501568 blocks [2/1] [_U]
/dev/md4 is an active, raid1 array with component device /dev/sdc2 [device 1]
out of 2 devices, 1 is in in use, device 0 is down and device 1 is up

md0 : active raid1 sdb2[1] sda2[0]
      45761088 blocks [2/2] [UU]
/dev/md0 is an active, raid1 array with component devices /dev/sdb1 [device 1] and  /dev/sda2  [device 0]
out of 2 devices, 2 are in use, and both are Up

sdx# is partition # on scsi device x
0
 

Author Comment

by:Shen
ID: 40594462
So if I undertand it:
   the raids  names are the dev/md0..4  
  and  dev/sdbx[] , dev/sdax[], dev/sdcx[], dev/mdx[] are partitions of sdb, sda,  sdc, md  physical devices since the machines has 4 physical drives?
0
 

Author Comment

by:Shen
ID: 40594504
Please forget my previous response:

After reading your explanation more:

all the sdbx,sdax,sdcx, mdx are partitions in 2  devices [0] or [1]. Each devices (0,1) is raid 1, so this makes 4 physical drives.
0
Master Your Team's Linux and Cloud Stack!

The average business loses $13.5M per year to ineffective training (per 1,000 employees). Keep ahead of the competition and combine in-person quality with online cost and flexibility by training with Linux Academy.

 
LVL 84

Accepted Solution

by:
ozo earned 500 total points
ID: 40594584
I would guess that md2 and md4 would normally have a mirror on /dev/sdd#, and that this is the drive that failed.
0
 

Author Closing Comment

by:Shen
ID: 40598144
thanks.  Do you suggest any tools to fix the drive
0
 

Expert Comment

by:Saravanan Palanisamy
ID: 40675066
Use mdadm command utility to replace the failed drive.
0

Featured Post

Use Case: Protecting a Hybrid Cloud Infrastructure

Microsoft Azure is rapidly becoming the norm in dynamic IT environments. This document describes the challenges that organizations face when protecting data in a hybrid cloud IT environment and presents a use case to demonstrate how Acronis Backup protects all data.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Setting up Secure Ubuntu server on VMware 1.      Insert the Ubuntu Server distribution CD or attach the ISO of the CD which is in the “Datastore”. Note that it is important to install the x64 edition on servers, not the X86 editions. 2.      Power on th…
Google Drive is extremely cheap offsite storage, and it's even possible to get extra storage for free for two years.  You can use the free account 15GB, and if you have an Android device..when you install Google Drive for the first time it will give…
Learn several ways to interact with files and get file information from the bash shell. ls lists the contents of a directory: Using the -a flag displays hidden files: Using the -l flag formats the output in a long list: The file command gives us mor…
Connecting to an Amazon Linux EC2 Instance from Windows Using PuTTY.

832 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question