Understanding device error busy error:

# lsof | grep '/dev/sda1'

Output:

vi 4453       vivek    3u      BLK        8,1                 8167 /dev/sda1

# umount /dev/sda1

Following disussion allows you to unmout device and partition forcefully using Linux commands.

Linux fuser command to forcefully unmount a disk partition:

Suppose you have /dev/sda1 mounted on /mnt directory then you can use fuser command as follows:

Type the command to unmount /mnt forcefully:

# fuser -km /mnt

Where,

• -k : Kill processes accessing the file.
• -m : Name specifies a file on a mounted file system or a block device that is mounted. In above example you are using /mnt

Linux umount command to unmount a disk partition You can also try umount command with –l option:

# umount -l /mnt

Where,

• -l : Also known as Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. This option works with kernel version 2.4.11+ and above only.

If you would like to unmount a NFS mount point then try following command:

# umount -f /mnt

• -f: Force unmount in case of an unreachable NFS system

[root@localhost ~]# pvcreate /dev/sdb /dev/sdc /dev/sdd
Physical volume “/dev/sdb” successfully created
Physical volume “/dev/sdc” successfully created
Physical volume “/dev/sdd” successfully created

 
pvs
[root@localhost ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 rhel lvm2 a– 39.51g 0
/dev/sdb lvm2 a– 20.00g 20.00g
/dev/sdc lvm2 a– 20.00g 20.00g
/dev/sdd lvm2 a– 20.00g 20.00g

vgcreate backupvg /dev/sdb
[root@localhost ~]# vgcreate backupvg /dev/sdb
Volume group “backupvg” successfully created

vgs

[root@localhost ~]# vgs
VG #PV #LV #SN Attr VSize VFree
backupvg 1 0 0 wz–n- 20.00g 20.00g
rhel 1 2 0 wz–n- 39.51g 0

lvcreate -n lv_optback -L +5G backupvg

[root@localhost ~]# lvcreate -n lv_optback -L +5G backupvg
Logical volume “lv_optback” created

 
lvcreate -n lv_varback -L +5G backupvg

[root@localhost ~]# lvcreate -n lv_varback -L +5G backupvg
Logical volume “lv_varback” created
[root@localhost ~]# mkfs.xfs /dev/backupvg/lv_optback
meta-data=/dev/backupvg/lv_optback isize=256 agcount=4, agsize=327680 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=1310720, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=12800, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0

[root@localhost ~]# mkdir /optback
root@localhost ~]# mount /dev/backupvg/lv_optback /optback/
[root@localhost ~]# df -TH
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs 39G 4.1G 35G 11% /
devtmpfs devtmpfs 4.2G 0 4.2G 0% /dev
tmpfs tmpfs 4.2G 95k 4.2G 1% /dev/shm
tmpfs tmpfs 4.2G 39M 4.1G 1% /run
tmpfs tmpfs 4.2G 0 4.2G 0% /sys/fs/cgroup
/dev/sda1 xfs 507M 109M 398M 22% /boot
/dev/mapper/backupvg-lv_optback xfs 5.4G 34M 5.3G 1% /optback

[root@localhost ~]# lvextend -L +2G /dev/backupvg/lv_optback
Extending logical volume lv_optback to 7.00 GiB
Logical volume lv_optback successfully resized

root@localhost ~]# xfs_growfs /optback
meta-data=/dev/mapper/backupvg-lv_optback isize=256 agcount=4, agsize=327680 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0
data = bsize=4096 blocks=1310720, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal bsize=4096 blocks=12800, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 1310720 to 1835008

[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 36G 3.8G 32G 11% /
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 92K 3.9G 1% /dev/shm
tmpfs 3.9G 38M 3.8G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 484M 104M 380M 22% /boot
/dev/mapper/backupvg-lv_optback 7.0G 33M 7.0G 1% /optback

Red Hat Enterprise Linux 7 BETA 1 Install and overview | A good thing even better
Red Hat is the leader in development, deployment, and management of Linux and open-source solutions for Internet infrastructure – ranging from embedded devices to secure web servers. The company was founded in 1994 by visionary entrepreneurs Bob Young and Marc Ewing. Open source is the foundation of its business model as it represents a fundamental shift in how software is created. The code that makes up the software is available to anyone and developers who use the software are free to improve it. The result: rapid innovation. Red Hat solutions combine Red Hat Linux, developer and embedded technologies, training, management services, technical support. The company is headquartered in Raleigh, North Carolina, USA.

Download
http://ftp.redhat.com/redhat/rhel/beta/7/

Red Hat Enterprise Linux (RHEL), the Linux vendor’s core platform, had its last major release with the debut of RHEL 6 in November of 2010. Red Hat has been releasing major new RHEL platforms every two to three years, and at its 2012 Summit event the company had hinted that 2013 could be the year in which RHEL 7 might be released.

As it turns out, the exact timing for the general availability of RHEL 7 is still in question. Ronald Pacheco, Senior Manager, Technology Product Management at Red Hat, said that his company has been working on RHEL 7 for a long time.

He stressed that RHEL 6 and 5 are still strong platforms and are being updated and iterated. RHEL 6.4 for example was recently released, providing new Microsoft interoperability capabilities.

XFS

In terms of features, RHEL 7 will mark a departure on a number of fronts from previous Red Hat releases.

Ric Wheeler, Kernel File and Storage Team Senior Manager and Architect at Red Hat, told the capacity crowd that the XFS filesystem will be the new default in RHEL 7 instead of EXT4.

Previously there had been some discussion that perhaps the Btrfs filesystem could play a big role in the upcoming Linux release, though Wheeler said the plan is now to make sure that Btrfs is in shape so it can be included as an option.

From a Linux kernel perspective, Wheeler hinted that from a timing perspective the Linux 3.11 kernel is likely the one that would power RHEL 7. The most recent generally available kernel right now in the upstream Linux community is Linux 3.9, with 3.10 set to debut in the coming weeks.

Secure Boot

From a hardware enablement perspective, Peter Martuccelli, Senior Engineering Manager for Platform Enablement at Red Hat, said that RHEL 7 will support UEFI and Secure Boot.

RHEL 7 will also include the Hardware Error Reporting Mechanism [HERM], which aims to improves server logging mechanisms by integration with various hardware error input methods.

Networking

One of the biggest areas of improvement in RHEL 7 is likely to be networking services.

Rashid Kahn, Senior Engineering Manager for networking services at Red Hat, joked with the audience that from his perspective RHEL 7 is in fact, “all about networking.”

One of the major new improvements is the addition of the Team Driver. Kahn explained that the driver combines multiple networking interfaces into a single interface. The goal of the driver is to provide improved throughput, networking redundancy and easier management.

The Precision Time Protocol (PTP) will also land in RHEL 7. PTP was available as a technology preview in RHEL 6.4 and is expected to be fully supported in RHEL 6.5.

“If time is money, you might want to try PTP precision time protocol,” Kahn said.

PTP can have a use-case in high-frequency trading as it ensures precise sub microsecond synchronization of distributed clocks over the network.

The other big addition set to land in RHEL 7 is the inclusion of Open vSwitch support. Open vSwitch is an open source virtual switch that initially became available in the upstream Linux kernel with the Linux 3.3 release in March of 2012.

Kahn said that Open vSwitch will be a tech preview in RHEL 6.5 and will be fully supported in RHEL 7.

Speaking of the biggest changes that the new file system – XFS will replace ext4 – The main reason for the XFS supports up to 500TB, and ext4 only supports 50TB.

As XFS file system performance when dealing with a large number of small files how, is still unclear, but administrators also need to learn how to manage it.

According to RHEL 7.0 release notes, this version includes major changes :

Contains Kernel 3.10 version supports swap memory compression can guarantee a significant reduction in I / O and improve performance, the use of NUMA (uniform memory access) scheduling and memory allocation, support for APIC (Advanced Programmable Interrupt Controller) virtualization, comprehensive DynTick support

The kernel module blacklisted, kpatch dynamic kernel patch (Technology Preview), and so on.
Storage and file systems, RHEL 7.0 kernel use LIO target subsystem that supports fast cache for the slower devices block devices, the introduction of the LVM cache (Technology Preview),
the XFS as the default file system.The introduction of a network packet technology as an alternate method of link aggregation bundles, extensive improvements for NetworkManager provides
dynamic firewall daemon firewalld, adding DNSSEC Domain Name System Security Extensions, with OpenLMI used to manage Linux systems provide common infrastructure, the introduction of credible Network connectivity (Technology Preview) and so on.

On KVM (Kernel-based virtualization) provides a number of improvements, such as using virtio-blk-data-plane to improve fast I / O performance (technology preview),
supports PCI bridge, QEMU sandbox, multi-queue NIC, USB 3.0 support ( Technology Preview) and so on.

Introducing Linux container Docker.

Compiler tool chain, RHEL 7.0 contains GCC 4.8.x, glibc 2.17, GDB 7.6.1.

Includes Performance Co-Pilot, SystemTap 2.4, Valgrind 3.9.0 and other performance tools.

Includes Ruby 2.0.0, Python 2.7.5, JAVA 7 other programming languages.

Includes Apache 2.4, MariaDB 5.5, PostgreSQL 9.2 and so on.

On systems and services, RHEL 7.0 using systemd replaced SysV.

Pacemaker cluster manager introduced while using keepalived and replace HAProxy load balancing procedures Piranha.

In addition, the Anaconda installation program has been redesigned and enhanced, and use the boot loader GRUB 2.

RHEL 7.0 supports 64-bit AMD / Intel, IBM POWER7/POWER8/System z and other architecture from its official website to download an evaluation version .
Red Hat ‘s source code directly RHEL7 released to the CentOS on site, in view of the fact Centos release of Red Hat is a community-funded,
Centos 7 should soon be released.