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Full Discussion: Raid0 array stresses only 1 disk out of 3
Top Forums UNIX for Dummies Questions & Answers Raid0 array stresses only 1 disk out of 3 Post 302970987 by chebarbudo on Thursday 14th of April 2016 10:45:21 AM
Old 04-14-2016
Hi guys,

Thank you very much for your contributions.

First of all, my problem does not happen any more. I created the raid with sdb, sdc and sdd on April 11 at 09:35.
Until 11:32, sdd was very busy, then until 14:51, sdc was very busy.
Since then (3 days), the 3 disks are always under the same moderate load altogether (0-20%). The server is used by 5 graphic designers manipulating quite large files (100M-2G).

I ran some tests and the results leave me quite puzzled. So I created simultaneously 10 files. 1GB each. But all the load went on sda. Leaving sdb, sdc and sdd with a moderate 20% load.

The command:
Code:
for i in {1..10}; do
  file=$(mktemp /galaxy/XXXXXXX)
  echo $file >> /galaxy/dd.files
  dd if=/dev/zero of=$file bs=1G count=1 &
  echo $!    >> /galaxy/dd.pids
done

The output of dstat:
Code:
----system---- sda--sdb--sdc--sdd-
     time     |util:util:util:util
14-04 15:56:30|  21:   0:   0:   0
14-04 15:57:00| 100:   0:   0:   0
14-04 15:57:30| 101:   0:   0:   0
14-04 15:58:00| 100:   2:   2:   1
14-04 15:58:30| 101:   3:   4:   2
14-04 15:59:00| 102:   4:   5:   4
14-04 15:59:30|  98:   2:   3:   2
14-04 16:00:00| 100:   4:   4:   2
14-04 16:00:30| 103:  16:  16:  15
14-04 16:01:00|  98:  16:  17:  15
14-04 16:01:30| 101:  15:  15:  15
14-04 16:02:00|  99:   9:   8:   8
14-04 16:02:30| 100:   3:   4:   3
14-04 16:03:00| 100:   2:   4:   3
14-04 16:03:30| 104:   4:   4:   3
14-04 16:04:00|  95:   4:   4:   3
14-04 16:04:30| 100:   3:   4:   2
14-04 16:05:00| 101:   3:   4:   3
14-04 16:05:30|  99:  12:  13:  12
14-04 16:06:00| 102:  20:  22:  18
14-04 16:06:30|  98:  17:  19:  18
14-04 16:07:00| 101:   7:   9:   8
14-04 16:07:30|  99:   4:   5:   3
14-04 16:08:00| 102:   4:   5:   3
14-04 16:08:30|  98:   3:   5:   3
14-04 16:09:00| 100:   5:   7:   5
14-04 16:09:30| 101:   5:   5:   4
14-04 16:10:00| 100:   4:   4:   2
14-04 16:10:30| 100:  17:  18:  16
14-04 16:11:01| 105:  16:  20:  16
14-04 16:11:30|  95:  15:  17:  17
14-04 16:12:00| 100:  12:  11:  10
14-04 16:12:30|  34:  15:  16:  14

Is /dev/zero an actual file of sda?
How do you interpret the results?

Regards
Santiago
 

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LEARN ABOUT REDHAT

usermount

USERMOUNT(1)						      General Commands Manual						      USERMOUNT(1)

NAME

       usermount - A graphical tool to mount, unmount and format filesystems.

SYNOPSIS

       usermount [ options ]

DESCRIPTION

       usermount is a graphical tool to allow users to easily manage removable media, such as floppy disks or zip disks.  When the tool starts up,
       it scans /etc/fstab for all filesystems that have been configured to allow users to mount and unmount them.  The filesystem can be  mounted
       or unmounted by pressing the toggle button labeled Mount.

       Also,  if  the user has the appropriate permissions for the device, the Format button will be active.  This allows the user to format disks
       using fdformat and create a new filesystem of the type listed (using mkfs with the  appropriate	option).   Naturally,  the  user  will	be
       prompted for confirmation before actually destroying data on the device.

       Note that if a device is already mounted, the format button is inactive for all entries that share the same device.

       When run as root, usermount displays all of the entries in /etc/fstab rather than just the ones with the user option.

OPTIONS

       This program has no command line options of it's own, but it does take the standard X program options like -display and such.  See the X(1)
       man page for some of the common options.

FILES

       /etc/fstab		The system file describing the mountable filesystems.

SEE ALSO

       mount(8), fdformat(8), mkfs(8), fstab(5) X(1)

BUGS

       Mount entries with a filesystem type of iso9660 are outright considered CD-ROMs and the format button is always disabled.

       Mount entries for swap files or partitions are also ignored.  A nice feature might be to allow root to turn swap on and off for swap parti-
       tions.

AUTHOR

       Otto Hammersmith <otto@redhat.com>

Red Hat Software						  3 October 1997						      USERMOUNT(1)
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