Visit The New, Modern Unix Linux Community

storage disk details

Thread Tools Search this Thread
Operating Systems Linux Red Hat storage disk details
# 1  
storage disk details


We have a OEL5.7 installed and which has a storage attached on it.
While running application it shows poor performance for Disk IO "dm-0"

Now the question is how do I find what exactly is "dm-0"

[root@~]# iostat
Linux 2.6.32-100.23.1.el5    03/10/2012

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           1.46    0.00    1.20    4.52    0.00   92.82

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              12.49        87.93       143.30   75059335  122323742
sda1              0.00         0.03         0.00      21774         30
sda2             12.49        87.90       143.30   75036897  122323712
dm-0              1.34         5.43         8.85    4636962    7556976
dm-1             27.11        82.47       134.44   70399536  114766736

[root@~]# fdisk -l

Disk /dev/sda: 30.9 GB, 30999052288 bytes
255 heads, 63 sectors/track, 3768 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14        3768    30162037+  8e  Linux LVM

[root@~]# cat /proc/partitions
major minor  #blocks  name

   8        0   30272512 sda
   8        1     104391 sda1
   8        2   30162037 sda2
 253        0   15269888 dm-0
 253        1   14876672 dm-1

Here are few commands I tried, but not able to know what exactly (mount point) dm-0 and dm-1 are referring to..

Please suggest...

Last edited by DukeNuke2; 03-09-2012 at 02:55 AM..
# 2  
have a look here:
DM Multipath
# 3  
Thanks DukeNuke2...

I just tried to search path to LUN's for current env.. got following output..

[root@ mapper]# multipath -l
Mar 10 03:14:48 | /etc/multipath.conf does not exist, blacklisting all devices.
Mar 10 03:14:48 | A sample multipath.conf file is located at
Mar 10 03:14:48 | /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf
Mar 10 03:14:48 | You can run /sbin/mpathconf to create or modify /etc/multipath.conf
Mar 10 03:14:48 | DM multipath kernel driver not loaded

I am actually new to this, can you please guide where exactly i need to search in system..

Warm regards!

Last edited by DukeNuke2; 03-09-2012 at 09:24 AM..
# 4  
dm-x is pretty much anything done through the device mapper. In your case I'm guessing it's one of the LVs. Do a ls -l /dev/mapper and look for the LV with the appropriate major and minor number.
# 5  
Thanks for the reply...

Here I can see is..
[root@ mapper]# ls -l /dev/mapper
total 0
crw------- 1 root root  10, 62 Feb 29 05:23 control
brw-rw---- 1 root disk 253,  0 Feb 29 05:23 VolGroup00-LogVol00
brw-rw---- 1 root disk 253,  1 Feb 29 05:23 VolGroup00-LogVol01

But, what I want to know is which storage actually dm-0 and dm-1 refer too...

Please help...
# 6  
Oh, that's easy. dm-0 corresponds to the logical volume VolGroup00-LogVol00. Since you have only one disk, and only one VG, it's the internal disk.
This User Gave Thanks to pludi For This Post:
# 7  
Thanks pludi,

So you mean dm-0 and dm-1 here are my hdd?
Also, where can i see the details of storage disk's then? we have configured it on our system..


Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #416
Difficulty: Medium
JavaScript supports event-driven, functional, and imperative (including object-oriented and prototype-based) programming styles.
True or False?

6 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Script to monitor the disk space details in HP-UX

Hi, I need to monitor the disk space details in HP-UX . I need a command on how to display the information on below format File System Total_Space_KB Used_Space_KB Available_Space_KB %Used /u05 524288000 376235344 138799427 73% /u02 ... (0 Replies)
Discussion started by: ali560045
0 Replies

2. AIX

Command to get Disk Adapter details in AIX

Hi, What is the command to get the disk adapter performance details in AIX?. Guide me. (2 Replies)
Discussion started by: maruthu
2 Replies

3. Solaris

Disk Storage Need to Add more Disk

Hi, Anyone can help me, just want to confirm, if possible adding a disk storage that we have a RAWDATA with +ASM in our database. If possible, what would you recommend "workaround used" from us to do and the preparation. And also how long the downtime will take. Our disk continuous to grow,... (0 Replies)
Discussion started by: fpalero
0 Replies

4. Solaris

Need Hard Disk Details

Hi freinds, What is the command to find out the hard disk details (logical name, FS type etc,). Because i connected one ntfs partition and i don't know the hard disk logical and physical name to mount it.Kindly do the needful. Thanks | P.Bharathiraja. :mad: (2 Replies)
Discussion started by: bharathiraja
2 Replies

5. Shell Programming and Scripting

Disk space details from Unix to Outlook

Hi Friends, I am using sun Solaris . I want to find the disk space (df -k) for the Unix box and the data has to be sent to an email id. Can u please find me a code that checks the disk space 6 times a day, loads the data into an excel sheet and sends to an email id. Can u also tell me how to... (2 Replies)
Discussion started by: sridharnr
2 Replies

6. UNIX for Dummies Questions & Answers

Details on available disk

Hi everybody.. I am looking for an alternative command to 'format' since this is allowed only to the root user. How do I do to get the same information as command format does here below ? AVAILABLE DISK SELECTIONS: 0. c0t0d0 <SUN146G cyl 14087 alt 2 hd 24 sec 848> ... (4 Replies)
Discussion started by: Riddick61
4 Replies

Featured Tech Videos