Linux For You Mate ...

Handling RAID 5 Failover, when 1 disk gets dead . As everything eventually does break (some sooner than others) a drive in the array will fail. It is a very good idea to run smartd on all drives in your array (and probably ALL drives period) to be notified of a failure or a pending failure as soon as possible. You can also manually fail a partition, meaning to take it out of the RAID array, suppose in your scenario " /dev/sdc1 " drive is faulty, then first we add another drive " /dev/sde " change it to "RAID auto detect partition", 1. Now here we make a RAID partition by, #fdisk /dev/sde Now, make a primary partition with full size and "fd" partition id. After creating RAID partition "/dev/sde1", it'll look like as below snap; 2. Next, we will detach faulty drive "/dev/sdc1" by, #mdadm /dev/md0 -f /dev/sdc1 3. Add new RAID partition "/dev/sde1" in RAID 5 device "/dev/md0", ...

How to extend LVM Volume online ? Note : If you see my current setting of LVM is as below; 1. Here with below command i am extending my "/dev/vg0_data/vol0_Data" volume by "2GB" #lvextend -L +2048M /dev/vg0_data/vol0_Data But to get that 2GB memory online you need to execute one more command, # resize2fs /dev/vg0_data/vol0_Data Now to verify, do as below in snap;    In LVM, online memory extend of LV is possible, but to reduce LV size will need a reboot. #lvreduce -L -1024M /dev/vg0_data/vol0_Data

Implimenting LVM over RAID 5  What is LVM : LVM stands for Logical Volume Manager, It is needed to be implimented if you want to increase your Logical Volume size in online (Increase without restart) condition, mostly in case of large production scenarios. In normal scenarios, we just setup server with normal "Ext3" to which we cant expand if it gets full. So here LVM concept comes. Why LVM on RAID 5 : To get data redundancy as well as online memory expand. As you saw in my previous article, how to impliment RAID 5 on RHEL / CentOS now next step is what you will do if you want Data redundancy as well as online memory expanding feature ? Yes, we impliment LVM over the RAID 5 volume. See below how ??? 1. Here i am assuming that we have successfully created a "/dev/md0" raid volume. 2. Now in LVM 1st we will create Physical Volume #pvcreate /dev/md0    Physical volume "/dev/md0" successfully created (Output) 3. Next create Volume Grou...

How to implement and configure RAID 5 on RHEL / CentOS ? What is RAID 5 : RAID-5 eliminates the use of a dedicated parity drive and stripes parity information across each disk in the array. Why we use RAID 5 : RAID-5 has become extremely popular among Internet and e-commerce companies because it allows administrators to achieve a safe level of fault-tolerance without sacrificing the tremendous amount of disk space necessary in a RAID-1 configuration or suffering the bottleneck inherent in RAID-4. RAID-5 is especially useful in production environments where data is replicated across multiple servers, shifting the internal need for disk redundancy partially away from a single machine. RAID level 5 can replace a failed drive with a new drive without user intervention. This functionality, known as Hot-spares. Also supports Hot-Swap, Hotswap is the ability to removed a failed drive from a running system so that it can be replaced with a new working drive. This means drive re...