Suppose you have added a new hard disk to your Linux OS running on any Virtual Environment which in my case is VMware workstation. Once added the new hard drive, generally the changes won’t reflect unless you reboot the Guest OS. But what if you are in no position to reboot the Gues Linux OS? In Full Article…
This HOWTO describes how to use Software RAID under Linux.
Mdadm Cheat Sheet
Mdadm is the modern tool most Linux distributions use these days to manage software RAIDarrays; in the past raidtools was the tool we have used for this. This cheat sheet will show the most common usages of mdadm to manage software raid arrays; it assumes you have a good understanding of software RAID and Linux Full Article…
Back to basics – Hot add new disk to Linux VM
In this post I’m going to detail how to add a new disk to an Ubuntu VM, online. Call it a “back to basics” post. First add another Hard-Disk to the guest as required. This will add a disk @ XX size, store it with the Guest VM files and it will be in persistent Full Article…
How to Configure Software RAID on Linux ?
Software RAID is one of the greatest feature in Linux to protect the data from disk failure.We have LVM also in Linux to configure mirrored volumes but Software RAID recovery is much easier in disk failures compare to Linux LVM. I have seen some of the environments are configured with Software RAID and LVM (Volume groups are built using RAID devices).Using Full Article…
How to scan new FC LUNS and SCSI disks in Linux ?
Scanning FC-LUN’s in Redhat Linux 1.First find out how many disks are visible in “fdisk -l” . # fdisk -l 2>/dev/null | egrep ‘^Disk’ | egrep -v ‘dm-‘ | wc -l 2.Find out how many host bus adapter configured in the Linux box.you can use “systool -fc_host -v” to verify available FC in the system. Full Article…
Rescanning your SCSI bus to see new storage
If you have added new storage to a running VM, you probably won’t see it. This is because the SCSI bus to which the storage devices are connected needs to be rescanned to make the new hardware visible. How you rescan the SCSI bus depends on the operating system your Virtual Machine is running. Instructions Full Article…
How to re-add accidentally removed hard drive in RAID5
When I try to run: sudo mdadm –manage /dev/md127 –re-add /dev/sdd1 It says: mdadm: –re-add for /dev/sdd1 to dev/md127 is not possible You might need to just do an –add and not a –re-add. if you read the man page about –re-add it talks about re-adding the device if the event count is close to Full Article…
RAID Software Partitioning-Creating the RAID Array-Preparing to Boot the Array-Copying the Data-Completing the RAID Array
In the first step we will create a degraded RAID1 array, which means a RAID1 array with one of the drives missing, using only the new drive. Next we will config the system to be able to boot from the new degraded RAID1 array and copy the data from the old drive to the RAID1 Full Article…
Linux Software Raid 1 Setup
1. Introduction This article describes step by step setup of Linux software RAID 1 on Linux Platform. Although this software RAID 1 configuration has been accomplished on Debian ( Ubuntu ) it also can guide you if you are running some other Linux distributions such as RedHat, Fedora , Suse, PCLinux0S etc. For RAID-1 setup we Full Article…
sfdisk
On a non GPT partition table I can do sfdisk -d /dev/sda | sfdisk /dev/sdb. But sfdisk doesn’t support GPT partition tables. What can I use instead? Install gdisk which is available in the Ubuntu Universe repositories. Then use the sgdisk command (man page here) to replicate the partition table: sgdisk -R /dev/sdY /dev/sdX sgdisk Full Article…
How Does a Raid 10 Array Work
If you need to implement a storage solution that supports I/O-intensive operations (such as database, email, and web servers), RAID 10 is the way to go. Let me show you why. Let’s refer to the below image. Imagine a file that is composed of blocks A, B, C, D, E, and F in the above Full Article…
create a software RAID-1 array with mdadm
Redundant Array of Independent Disks (RAID) is a storage technology that combines multiple hard disks into a single logical unit to provide fault-tolerance and/or improve disk I/O performance. Depending on how data is stored in an array of disks (e.g., with striping, mirroring, parity, or any combination thereof), different RAID levels are defined (e.g., RAID-0, Full Article…
Recovery of a degraded 3ware RAID-Controller with tw_cli
You have a RAID-1 with 2 disks and one disk fails. You change the failed disk and everything seems good as the disk starts recovery. But recovery stops as the old disk with data on it changes into state ECC-ERROR. So you have your data on a disk with status ECC-ERROR and a new disk Full Article…
Manage software RAID arrays
1. Create a new RAID array Create (mdadm –create) is used to create a new array: 1 mdadm –create –verbose /dev/md0 –level=1 /dev/sda1 /dev/sdb2 or using the compact notation: 1 mdadm -Cv /dev/md0 -l1 -n2 /dev/sd[ab]1 2. /etc/mdadm.conf /etc/mdadm.conf or /etc/mdadm/mdadm.conf (on debian) is the main configuration file for mdadm. After we create our RAID Full Article…
Mdadm: A New Tool For Linux Software RAID Management
raidtools has been the standard software RAID management package for Linux since the inception of the software RAID driver. Over the years, raidtools have proven cumbersome to use, mostly because they rely on a configuration file (/etc/raidtab) that is difficult to maintain, and partly because its features are limited. In August 2001, Neil Brown, a software Full Article…
How to Use MDADM Linux Raid
Create a 6 drive raid 5 array called /dev/md0 with chunk size of 16384: (typically, bigger chunk sizes are better for bigger files, default is 512) mdadm –create –level=5 –chunk=16384–raid-devices=6 /dev/md0 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg Assemble raid array that is not in the config file: mdadm –assemble /dev/md0 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf Full Article…
mdadm cheat sheet
create a new array mdadm –create /dev/md0 –level=1 –raid-devices=2 /dev/sda1 /dev/sdb1 or… mdadm -C /dev/md0 -l1 -n2 /dev/sd[ab]1 add array to the configuration file: mdadm –detail –scan >> /etc/mdadm.conf or on debian (sigh)… mdadm –detail –scan >> /etc/mdadm/mdadm.conf can only remove failed disks from an array, so fail a disk: mdadm –fail /dev/md0 Full Article…