Our expertise includes dns, dnssec, system administration and software development. This approach probably fails at this point with a some degraded arrays, since the grub install will proceed to tell each mbr to load the physical location of boot grub phase2 etc but it appears to determine that physical location independently of where. After first boot, consider executing dpkgreconfigure. To have grub rescan all of the devices and regenerate the bootgrubdevice. How to use mdadm to create a software mirror on top of. The state of the active linux software raid devices can be viewed by running. Raid devices should be assembled by the kernel before any. I had a look on the net and ive found out that it is a problem with software raid and grub, they. You tagged softwareraid, so learning grub can help. Enter for sda1 and sda2 type the appropriate size in mib i. Installing grub2 on gnulinux software raid sinodun. When the bootloaderstep is entered i selected grub2 each time i loaded a new raid. Im not aware of support in grub to declare two disks as being in a raid1 array.
But, somehow, for reasons i do not yet understand, the behavior changed even before i made that change to the device. But grub2 is more userfriendly, grubmkconfig will automatically changes the configuration. That means that grub cannot run off a software raid 0. When asked to install bootloader, install to first device.
Replacing a failed drive in a linux software raid1. Even if one of the disks in the raid array fails, the system can still boot. Setting up a bootable multidevice raid 1 using linux. Software raid on red hat enterprise linux v6 installation, migration and recovery. This guide explains how to set up software raid1 on an already running. Reinstall grub 2 substitute the correct device with sda, sdb, etc. How to change boot drive on server with raid 5 software raid. Linux handles raid and syncs the two boot partitions. There is no operational downside to having grub on a raid1 setup. When you specify the option devicemap see basic usage, the grub shell creates the device map file automatically unless it already exists. Grub vs grub2 bootloader learn the main difference. It generates this mapping with a help of an algorithm and saves it to the file device. This is the contents of the device map bootgrubdevice. Given that the order in which the bios addresses ide, scsi, and other hard drives depends on several.
How do i install grub on a raid system installation. Software raid raid that is is implemented at the software layer without a dedthe need foricated. For sda3 just hit enter to select the remainder of the disk select linux raid as the partition type. Installing grub2 on gnulinux software raid sinodun internet. The filesystems on the raid devices are ext2 voor devmd0 for boot. As boot loader, grub in this case, does not know anything about software raid that is managed. If you have multiple dmraid devices with multiple sets of arrays set up say.
If the device map file exists, the grub utilities grubprobe, etc. The grub used in f17 should automatically detect the right devices without using device. Use the mdadm command to create the md raid device. If you are using grub instead of lilo, then just start grub and configure it to use the. This approach probably fails at this point with a some degraded arrays, since the grubinstall will. On my other drive which i plan on removing the raid is initialized and mounted fine on boot, but its not the bootroot for that setup. Make sure that your grub configuration doesnt hardcode disks like hd0, but instead searches for the boot and root filesystems uuids. It still does not boot from the software raid 1, but from one of the raid.
I have my hardwareowned dedicated server hosted in remote datacenter, running centos release 6. I have been setting up a two machines with software raid to use as xen. In grub, partition number starts from 0, whereas in grub2 it starts with 1. Grub2installing community help wiki ubuntu documentation. After hardware or hardware settings changed, you may sometimes need to force grub to rescan devices. How to create a softwareraid with ubuntu the main tool is mdadm in ubuntu 11. Grub rescue shell with raid 6 mdadm over 8 disks request was from steve mcintyre. Server has 6 2tb drives with 2 software raids on them md0 raid 1. So the goal of this howto is to put the partition table, and boot, root, and swap partitions on bootable raid1 mirror device. This article describes how to setup a linux system that can boot directly from a software raid1 device using grub. The device map is not installed by default with grub2. You can create a device map by typing the following into your console. This guide explains how to set up software raid1 on an already running lvm system debian squeeze. Now we need to make a note of the raid array device on which your linux partition exists it will be listed as a hard disk which is the total.
Linux software raid or md raid can be used as a boot device. How to set up software raid1 on a running system incl. Grub isnt actually using it as raid 1 when booting i. Historically, the device map file was used because grub device names had to be used in the configuration file, and they were derived from bios drive numbers. In my opinion such a partition layout should either be impossible to create with di or at. View topic solved installing grub2 with boot on software raid. Create alternate lvm based bootos environment alternatively, to mattis suggested usage of the entries swapped device.
Solved cant install grub2 on software raid my several installs of raid0 utilized grub 2 with no problems. By default it tries my first disk, which gives a fatal error. Festplattenaustausch im softwareraid hetzner dokuwiki. How to set up software raid1 on a running lvm system incl. If any of the lines is incorrect, fix it and rerun the. In the event of a failure you can boot fine off the second disk because it has an identical copy of the original boot partition. Grub for software raid howtoforge linux howtos and tutorials. Assuming the normal system partitions are on a software raid.
For crypto and raid md additionally you can use the syntax uuid. The grub2 bootloader will be configured in such a way that the system will still be able to boot if one. But, somehow, for reasons i do not yet understand, the. You need to either use a real hardware raid controller or use software raid 1. Note that in linux software raid you can create raid arrays by mirroring partitions and not entire disks. After that, devmd4 will be mapped to hd0 in the currently running grub session, disregarding the device map file. Ive a 60gig ide 1st primary device and scsi dvd on secondary slave. Im not aware of support in grub to declare two disks as being in a raid 1 array so that grub install would automatically write to both. Festplattenaustausch im softwareraiden hetzner dokuwiki. The raid is active but is not using the multipath devices as expected. Advantagesdisadvantages of installing grub on a software. Linux software raid disc replacement procedure web and. Changed bug title to grub boot on large software raid systems may break due to bios limitations from grub2. The disks are appended to each other, so writing linearly to the raid device will fill up disk 0 first.
Since the serial number of the disk changed we need to generate a new devicemap with grub2. The problem is at the end of the installation, it tries to install grub. Sinodun is a research and development company primarily focused on internet protocols. Grub boot on large software raid systems may break due to. Grub legacy identifies hdd devices in the bootgrubdevice. However, grub both legacy and grub2 fail to generate a device mapping for md0, thus being unable to install grub. This howto describes how to use software raid under linux. This is the one advantage of having grub over raid1, but its a big one. Now lets create our raid arrays devmd0, devmd1, and devmd2.
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