Davoud Teimouri - Virtualization & Datacenter

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Category: How To

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kernel: WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xbb/0xe0 – Oracle Enterprise Linux

Most of modern servers hardware are using UEFI instead of legacy BIOS and modern OS has dedicated partition to stores boot and EFI values.

Some times, the partition gets full or OS generate the below log:

kernel: WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xbb/0xe0

Kernel includes a CONFIG_EFI_VARS_PSTORE feature, and a feature that dumps kernel message log (= the “dmesg” command output) into UEFI variables for persistent storage if the system is crashing (or even if the system is working normally, depending on the options chosen).

The cause of the warning is duplicate dump file in EFI partition and OS is trying to write values on same file.

There is a simple solution, remove old dump file!

I hope this article help you to find out root cause of the warning and resolve that.

Here is the complete log on our virtual machine:

kernel: WARNING: at lib/kobject.c:196 kobject_add_internal+0x205/0x260()
kernel: Hardware name: VMware7,1
kernel: kobject_add_internal failed for dump-type2-0-0-1493749396-cfc8fc79-be2e-4ddc-97f0-9f98bfe298a0 with -EEXIST, don’t try to register things with the same name in the same directory.
kernel: Modules linked in: vmw_vsock_vmci_transport vsock oracleasm autofs4 ipv6 vfat fat uinput vmw_balloon coretemp crc32c_intel ghash_clmulni_intel microcode pcspkr sg ixgbe hwmon dca vmw_vmci i2c_piix4 shpchp ext4 jbd2 mbcache dm_round_robin scsi_dh_emc sd_mod crc_t10dif sr_mod cdrom aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul vmxnet3 qla2xxx scsi_transport_fc scsi_tgt mptspi mptscsih mptbase scsi_transport_spi pata_acpi ata_generic ata_piix vmwgfx ttm drm i2c_core dm_multipath dm_mirror dm_region_hash dm_log dm_mod scsi_dh_alua [last unloaded: speedstep_lib] kernel: Pid: 5934, comm: kworker/60:2 Tainted: G        W    3.8.13-16.2.1.el6uek.x86_64 #1
kernel: Call Trace:
kernel: [<ffffffff8105d2af>] warn_slowpath_common+0x7f/0xc0
kernel: [<ffffffff8105d3a6>] warn_slowpath_fmt+0x46/0x50
kernel: [<ffffffff81286865>] kobject_add_internal+0x205/0x260
kernel: [<ffffffff81286a78>] kobject_add_varg+0x38/0x60
kernel: [<ffffffff81286af3>] kobject_init_and_add+0x53/0x70
kernel: [<ffffffff8128f140>] ? sprintf+0x40/0x50
kernel: [<ffffffff814755ec>] efivar_create_sysfs_entry+0x12c/0x1b0
kernel: [<ffffffff81475b95>] efi_pstore_write+0x1b5/0x200
kernel: [<ffffffff81214b48>] pstore_console_write+0xd8/0x100
kernel: [<ffffffff8105e027>] ? msg_print_text+0xc7/0x1e0
kernel: [<ffffffff8105f063>] call_console_drivers.clone.3+0xa3/0x100
kernel: [<ffffffff8105f4c4>] console_unlock+0x274/0x2c0
kernel: [<ffffffff8105fa75>] vprintk_emit+0x325/0x520
kernel: [<ffffffff8109e5f6>] ? find_busiest_group+0x36/0x4d0
kernel: [<ffffffff8138a189>] dev_vprintk_emit+0x69/0x90
kernel: [<ffffffff8109ebbe>] ? load_balance+0x12e/0x670
kernel: [<ffffffff8138a1e9>] dev_printk_emit+0x39/0x40
kernel: [<ffffffff81079e6f>] ? insert_work+0x3f/0x60
kernel: [<ffffffff8138a22e>] __dev_printk+0x3e/0x90
kernel: [<ffffffff8138a565>] dev_printk+0x45/0x50
kernel: [<ffffffff81048099>] ? default_spin_lock_flags+0x9/0x10
kernel: [<ffffffffa0116939>] fc_timeout_deleted_rport+0x229/0x350 [scsi_transport_fc] kernel: [<ffffffff8107b6f0>] process_one_work+0x180/0x410
kernel: [<ffffffff8107d71e>] worker_thread+0x12e/0x390
kernel: [<ffffffff8107d5f0>] ? manage_workers+0x180/0x180
kernel: [<ffffffff81082a6e>] kthread+0xce/0xe0
kernel: [<ffffffff810829a0>] ? kthread_freezable_should_stop+0x70/0x70
kernel: [<ffffffff8159b66c>] ret_from_fork+0x7c/0xb0
kernel: [<ffffffff810829a0>] ? kthread_freezable_should_stop+0x70/0x70
kernel: —[ end trace 940656e1b6e55a3d ]—

OS information:

OEL 6.5 and kernel is 3.8.13-16.2.1.el6uek.x86_64

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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Monitoring Temperature And Fan Speed In Linux By LM-Sensors

What’s LM-Sensors

Health monitoring is very important for critical servers because administrators can do proper actions before any impact on service. There is many third-party software for monitoring Linux and Windows servers but native agents are also useful.

We are going to review one of native solutions for hardware health monitoring in Linux.
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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

2,206 total views, 6 views today

Find, Convert And Compare, VMware Virtual Machine And Windows Guest UUID

What’s UUID?

Each virtual machine has UUID and it will appear on OS as guest UUID too.

A universally unique identifier (UUID) is a 128-bit number used to identify information in computer systems, the 16 bytes of this value are separated by spaces. Microsoft uses the term globally unique identifier (GUID), either as a synonym for UUID or to refer to a particular UUID variant.

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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,208 total views, 7 views today

Remove Multipath Device – Map in use!

Multipath Device, Remove From Linux

Based on Red Hat solution (https://access.redhat.com/solutions/47438), the below steps should be done before flush any multipath device, otherwise the command will be failed:

  • Locate any subsystem or process holding the multipath device open.
  • For any subsystem or process holding the multipath device open, stop the process, or issue commands to release the multipath device.
  • Some examples of possible holders of a multipath device and the commands to release it:
  • One or more partition mapping(s) still exists on the multipath device.
    • Use “kpartx -d” on the multipath device to remove the device partition mapping(s).
  • A filesystem exists on the multipath device and is currently mounted.
    • Unmount the filesystem and if it exists in /etc/fstab, remove it.
  • The multipath device was used by LVM, and still has device mapper state in the kernel.
    • Use “lvchange -an” to deactivate any logical volume(s) associated with the multipath device.  A list of logical volumes associated with the multipath device may be found by examining the output of “lvs -o +devices“.
    • If “lvchange -an” fails, the logical volume is only partially removed, or there are blocked processes with I/O outstanding on the device, use “dmsetup remove -f” followed by “dmsetup clear” on the multipath device.  See dmsetup man page for full explanation of these commands.

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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,319 total views, 20 views today

Installing Arch Linux Using Arch Anywhere – Part 2

This post is 2nd part of Arch Linux installation guide and as you may read the first part, you know that we want to do it by Arch Anywhere and now, if you have downloaded ISO from Arch Anywhere website, mount it and follow the below steps. I’ll install Arch Linux on a virtual machine, you can do it on virtual machine or physical machine.

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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,959 total views, 15 views today

Installing Arch Linux Using Arch Anywhere – Part 1

Arch Linux is one of most popular Linux distributions and one of most updated Linux distributions.

Arch Linux has no graphical or automatic installer for installation and installing Arch Linux is not simple for most new users.

During installation, you have to do initialize disk, create partitions, configure boot-loader and other configurations manually. So you need to know enough about Linux. If you know, what are you doing, it would be wonderful experience but if not, it will be dark dream!

Now, what’s solution to gain experience of working with most updated Linux for beginner users?

Answer, you can use Arch Anywhere to install Arch Linux.

What’s Arch Anywhere? 

Arch Anywhere contains a script to give you ability to install Arch Linux with very customization and of course, all things will be automated.


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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

3,791 total views, 14 views today

Find HBA Firmware Version in Linux – Easy Way

You need to know, what is version of your HBA firmware to upgrade it or install compatible driver version.

There is many ways to find firmware version but I want to share easier way.

Just logon to your Linux machine with Sudo user and run the below command:

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Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,919 total views, 7 views today

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