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Iostat output on my system:

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.13    0.02    0.42    0.32    0.10   99.01

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
xvdap1            1.29        32.67        10.06   27432377    8450380

But if we examine lsblk, we do not find a device named xvdap1:

NAME  MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda1 202:1    0   8G  0 disk /

Moreover, xvdap1 cannot be found in /dev/:

user@host:~$ ls /dev/xvd*
/dev/xvda1

I'm inclined to believe that xvdap1 is the same as /dev/xvda1, but why on earth would they have two different names? It is a problem, because i get partitions which mounted from /proc/mounts and there are not describe xvdap1, only xvda1. And if i pass /dev/xvda1 request to iostat, f.e.:

iostat -p /dev/xvda1

He nothing output.

2 Answers2

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xvdap1 is xvda1 This seems to be weirdness with how iostat is displaying the devicename. If you run iostat -p /dev/xvda1 and then iostat you should see the exact same numbers for the xvdap1 and xvda1 devices:

$ iostat -p /dev/xvda1

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
xvda1             0.26         0.07         2.66     258713   10327556

$ iostat 

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
xvdap1            0.26         0.07         2.66     258713   10327556
xvdb              0.00         0.00         0.00        684          0
xvdf              0.77         0.10         5.43     403313   21062404
xvdg              0.00         0.00         0.00        684          0
MHKid
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While i can't answer Why, the behaviour is defined in https://github.com/sysstat/sysstat/blob/master/sysstat.ioconf

in particular a line:

202:xvd:*:0:a:16:p:16:Xen Virtual Block Device

The description is in the start of a file and goes like this:

#  This file gives iostat, sar, and sadf a clue about how to find whole
#  disk devices in /proc/diskstats.
#  partpre:             appended to whole dev before part designator
#                        eg. the p in c0d2p6, decimal formatting implied
#            '*' means none
bromi
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