dm0 in iostat???

your_shadow03 · 07-01-2008, 03:59 AM

Hey Guys,

One of our Performance testing team need help on iostat output:
They are unable to understand what dm0 means in iostat output:

Code:

What  below output does mean

 

 

[root@BL10DL385 dev]# iostat

Linux 2.6.9-67.ELsmp (BL10DL385.mailserver.com)         07/01/2008      _x86_64_

 

avg-cpu:  %user   %nice %system %iowait  %steal   %idle

           0.81    0.00    0.18    0.19    0.00   98.82

 

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn

cciss/c0d0       12.86       163.74       625.36   54100608  206627140

dm-0              0.25         0.54         1.88     177802     620248

dm-1              0.22         0.75         1.66     246330     548624

dm-2              0.00         0.00         0.00        754         16

dm-3              0.08         0.01         0.65       2258     214824

dm-4              0.20         3.64         0.83    1202122     275696

dm-5              0.00         0.01         0.00       2106        600

dm-6              0.23         0.58         1.59     192114     525368

dm-7             15.57        76.18        48.37   25172440   15981352

dm-8              0.39         0.01         3.12       2378    1031728

dm-9              2.02         0.01        16.12       1690    5327184

dm-10             0.36         0.23         2.83      74786     934416

dm-11             0.00         0.01         0.00       4930       1528

dm-12            39.49        81.31       310.62   26865338  102634160

dm-13            29.69         0.26       237.23      84634   78383704

dm-14             0.00         0.00         0.00       1370         56

dm-15             0.06         0.15         0.45      47986     147632

 

[root@BL10DL385 dev]# fdisk -l

 

Disk /dev/cciss/c0d0: 146.7 GB, 146745262080 bytes

255 heads, 63 sectors/track, 17840 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

 

           Device Boot      Start         End      Blocks   Id  System

/dev/cciss/c0d0p1   *           1          13      104391   83  Linux

/dev/cciss/c0d0p2              14       17840   143195377+  8e  Linux LVM

[root@BL10DL385 dev]#

Code:

[root@BL10DL385 dev]# fdisk -l

Disk /dev/cciss/c0d0: 146.7 GB, 146745262080 bytes
255 heads, 63 sectors/track, 17840 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

           Device Boot      Start         End      Blocks   Id  System
/dev/cciss/c0d0p1   *           1          13      104391   83  Linux
/dev/cciss/c0d0p2              14       17840   143195377+  8e  Linux LVM

Pls Help

Mr. C. · 07-01-2008, 04:13 AM

Logical volume managers' logical volumes: dm0 - dm6.

your_shadow03 · 07-01-2008, 04:16 AM

What does it means? Can You elaborate ??

your_shadow03 · 07-01-2008, 04:17 AM

Is it showing good status??

Mr. C. · 07-01-2008, 04:20 AM

Your system is almost completely idle. Run man iostat to learn about each field.

Utilities like iostat/vmstat/netstat are mostly meaningless until you become familiar with their output under various load conditions, ranging from none, to heavily loaded.

Download the bonnie++ benchmarks to get a feel for how the numbers look under load. Bonnie will also give you its benchmark results.

your_shadow03 · 07-01-2008, 04:31 AM

I have downloaded boniee++
but donno know how to use it.
[root@BL11DL385 ~]# cd /opt
[root@BL11DL385 opt]# ls
bonnie++-1.03c.gz
[root@BL11DL385 opt]# gunzip bonnie++-1.03c.gz
[root@BL11DL385 opt]# ls
bonnie++-1.03c
[root@BL11DL385 opt]# cd bonnie++-1.03c
-bash: cd: bonnie++-1.03c: Not a directory
[root@BL11DL385 opt]# ls
bonnie++-1.03c

RichardBronosky · 08-28-2009, 02:44 PM

Quote:

Originally Posted by Mr. C.

Logical volume managers' logical volumes: dm0 - dm6.

More specifically, if you want to know what each dm maps to, you can awk it together like so:

Code:

~# sudo lvdisplay|awk  '/LV Name/{n=$3} /Block device/{d=$3; sub(".*:","dm-",d); print d,n;}'
dm-0 /dev/SysVolGroup/LogVolRoot
dm-1 /dev/SysVolGroup/xen
dm-2 /dev/SysVolGroup/db1-2
dm-3 /dev/SysVolGroup/db1-2swap
dm-4 /dev/SysVolGroup/python1
dm-5 /dev/SysVolGroup/python1swap
dm-6 /dev/SysVolGroup/db1-2snap