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