Software RAID and LVM - Arch. Wiki. This article will provide an example of how to install and configure Arch Linux with a software RAID or Logical Volume Manager (LVM). The combination of RAID and LVM provides numerous features with few caveats compared to just using RAID. Introduction Warning: Be sure to review the RAID article and be aware of all applicable warnings, particularly if you select RAID5. Although RAID and LVM may seem like analogous technologies they each present unique features. This article uses an example with three similar 1. TB SATA hard drives. The article assumes that the drives are accessible as /dev/sda, /dev/sdb, and /dev/sdc. If you are using IDE drives, for maximum performance make sure that each drive is a master on its own separate channel. Tip: It is good practice to ensure that only the drives involved in the installation are attached while performing the installation. LVM Logical Volumes//var/swap/home. LVM Volume Groups/dev/Vol. Group. Array. RAID Arrays/dev/md. Physical Partitions/dev/sda. Hard Drives/dev/sda/dev/sdb/dev/sdc. Swap space Note: If you want extra performance, just let the kernel use distinct swap partitions as it does striping by default. Many tutorials treat the swap space differently, either by creating a separate RAID1 array or a LVM logical volume. Creating the swap space on a separate array is not intended to provide additional redundancy, but instead, to prevent a corrupt swap space from rendering the system inoperable, which is more likely to happen when the swap space is located on the same partition as the root directory. MBR vs. GPTSee also Wikipedia: GUID Partition Table. The widespread Master Boot Record (MBR) partitioning scheme, dating from the early 1. GUID Partition Table (GPT) is a new standard for the layout of the partition table based on the UEFI specification derived from Intel. Although GPT provides a significant improvement over a MBR, it does require the additional step of creating an additional partition at the beginning of each disk for GRUB2 (see: GRUB#GUID Partition Table (GPT) specific instructions). Boot loader. This tutorial will use SYSLINUX instead of GRUB. GRUB when used in conjunction with GPT requires an additional BIOS Boot Partition[broken link: invalid section]. GRUB supports the default style of metadata currently created by mdadm (i. ![]() Install Grub2 On Raid 1 Vs Raid 10Arch Linux with mkinitcpio. SYSLINUX only supports version 1. Some boot loaders (e. GRUB Legacy, LILO) will not support any 1. If you would like to use one of those boot loaders make sure to add the option - -metadata=0. RAID installation. Installation. Obtain the latest installation media and boot the Arch Linux installer as outlined in Category: Getting and installing Arch. Load kernel modules. IMPORTANT: If using Debian Woody (3.0) or later, you can install the package by running apt-get install raidtools2. (just like RAID-1). This page describes how to install Debian using the Serial ATA RAID (aka fake RAID. DebianInstaller/SataRaid. Enter another TTY terminal by typing Alt+F2. Load the appropriate RAID (e. LVM (i. e. dm- mod) modules. The following example makes use of RAID1 and RAID5. Prepare the hard drives.
Each hard drive will have a 1. MB /boot partition, 2. MB /swap partition, and a / partition that takes up the remainder of the disk. The boot partition must be RAID1; i. RAID0) or RAID5, RAID6, etc. This is because GRUB does not have RAID drivers. Any other level will prevent your system from booting. Additionally, if there is a problem with one boot partition, the boot loader can boot normally from the other two partitions in the /boot array. Install gdisk. Since most disk partitioning software (i. GPT you will need to install gptfdisk to set the partition type of the boot loader partitions. Install Grub2 On Raid 1 Vs Raid 2Update the pacman database. Refresh the package list. Install gptfdisk. Partition hard drives. We will use gdisk to create three partitions on each of the three hard drives (i. Name Flags Part Type FS Type [Label] Size (MB). Boot Primary linux_raid_m 1. Primary linux_raid_m 2. Primary linux_raid_m 9. Open gdisk with the first hard drive. Add a new partition: n Select the default partition number: Enter Use the default for the first sector: Enter For sda. MB (i. e. +1. 00. MB and +2. 04. 8M). For sda. 3 just hit Enter to select the remainder of the disk. Select Linux RAID as the partition type: fd. Write the table to disk and exit: w. Repeat this process for /dev/sdb and /dev/sdc or use the alternate sgdisk method below. You may need to reboot to allow the kernel to recognize the new tables. Note: Make sure to create the same exact partitions on each disk. If a group of partitions of different sizes are assembled to create a RAID partition, it will work, but the redundant partition will be in multiples of the size of the smallest partition, leaving the unallocated space to waste. Clone partitions with sgdisk. If you are using GPT, then you can use sgdisk to clone the partition table from /dev/sda to the other two hard drives. Note: When using this method to clone the partition table of an active drive onto a replacement drive for the same system (e. RAID drive replacement), use sgdisk - G /dev/< new. Drive> to re- randomise the UUID of the disk and partitions to ensure they are unique. RAID installation. After creating the physical partitions, you are ready to setup the /boot, '/swap, and / arrays with mdadm. It is an advanced tool for RAID management that will be used to create a /etc/mdadm. Create the / array at /dev/md. Create the /swap array at /dev/md. Note: If the only reason you are using RAID is to prevent stored data loss (i. RAID the swap partitions - - you can use them as multiple individual swap partitions. Note: If you plan on installing a boot loader that does not support the 1. RAID metadata make sure to add the - -metadata=0. Create the /boot array at /dev/md. Synchronization Tip: If you want to avoid the initial resync with new hard drives add the - -assume- clean flag. After you create a RAID volume, it will synchronize the contents of the physical partitions within the array. You can monitor the progress by refreshing the output of /proc/mdstat ten times per second with. Tip: Follow the synchronization in another TTY terminal by typing Alt+F3 and then execute the above command. Further information about the arrays is accessible with. Once synchronization is complete the State line should read clean. Each device in the table at the bottom of the output should read spare or active sync in the State column. Note: Since the RAID synchronization is transparent to the file- system you can proceed with the installation and reboot your computer when necessary. Scrubbing. It is good practice to regularly run data scrubbing to check for and fix errors. Note: Depending on the size/configuration of the array, a scrub may take multiple hours to complete. To initiate a data scrub. As with many tasks/items relating to mdadm, the status of the scrub can be queried. Personalities : [raid. UU]. [>..........] check = 4. K/sec. bitmap: 0/3. KB], 6. 55. 36. KB chunk. To stop a currently running data scrub safely. When the scrub is complete, admins may check how many blocks (if any) have been flagged as bad. The check operation scans the drives for bad sectors and mismatches. Bad sectors are automatically repaired. If it finds mismatches, i. This "do nothing" allows admins to inspect the data in the sector and the data that would be produced by rebuilding the sectors from redundant information and pick the correct data to keep. General Notes on Scrubbing Note: Users may alternatively echo repair to /sys/block/md. The danger is that we really don't know whether it's the parity or the data block that's correct (or which data block in case of RAID1). It's luck- of- the- draw whether or not the operation gets the right data instead of the bad data. It is a good idea to set up a cron job as root to schedule a periodic scrub. See raid- check. AUR which can assist with this. RAID1 and RAID1. 0 Notes on Scrubbing. Due to the fact that RAID1 and RAID1. These non- 0 counts will only exist in transient data areas where they don't pose a problem. How to correctly install GRUB on a soft RAID 1? In my setup, I have two disks that are each formatted in the following way: (GPT). MB BIOS_BOOT. 2) 3. MB LINUX_RAID. 3) * LINUX_RAID. The boot partitions are mapped in /dev/md. XFS. (I understand that formatting has to be done on the md devices and not on sd - please tell me if this is wrong). How do I setup GRUB correctly so that if one drive fails, the other will still boot? And by extension, that a replacement drive will automatically include GRUB, too? If this is even possible, of course.
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