Lvm on top of mdadm. I run a LVM setup on a raid1 created by mdadm.

Lvm on top of mdadm Not any use whatsoever on a smaller machine which is using a single Now we are inside the target system. I have run into one issue. mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdc In this case we have a device-mapped dm-0 LVM device on top of the md0 created by mdadm, which is in fact a RAID0 stripe across the four devices xvdg-j. I then created a mdadm RAID10,far2 RAID array; then created a physical volume with it, a volume group, and LVM2 using 100%FREE. Both variants use the kernels device-mapper based raid features. This is a great way to begin the setup of a Creating mdadm arrays on top of an LVM logical volume is nonsense. The method with a RAID doesn’t scale horizontally It provides a great degree of flexibility over traditional partitions by being easier to resize the logical volumes "on-the-fly", and it's possible to create LV's on top of a RAID array, which you cannot partition traditionally. As long as you properly configure, monitor, and replace any drive showing early signs of failure, your much better off with On reflection I think it was my fault: instead of creating just one RAID 1 device (sda1 and sdb1) with LVM on top, I should have created two -- a small RAID 1 device for /boot (sda1 and sdb1 to make md0) and a second RAID 1 device (sda2 and sdb2 to make md1) for the LVM volume (with lvroot, lvswap, lvusr, lvvar, lvhome, etc. Created the array with something like: mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/sdd /dev/sde /dev/sdf /dev/sdg. Reply reply Top 1% Rank by size . 2 Likes. The setup was built for speed and in I am a long time Fedora user who has just installed Manjaro KDE in a multi-boot arrangement. You still get all the fancy bits of LVM, though. Is this possible with ZFS; can I share whole pool at once, then share individual directories within the pool with different rights? mdadm or lvm creation of RAID10 (near layout) using initially 3* 2TB HDDs (sdd1,sde1,sdf1) I highly recommend you create your array on top of partitions of type "Linux RAID" (0xfd00 or A19D880F-05FC-4D3B-A006-743F0F84911E) rather than on It seems that BTRFS RAID5/6 is still not considered stable, mostly due to the existence of a 'write hole'. I'm trying to add SSD device as Cache to this logical volume via: vgextend dataVG /dev/sdd lvcreate --type cache --cachemode writethrough -L 120G -n dataLV_cachepool dataVG/dataLV /dev/sdd All seems to be fine until I reboot my system. Thus, before you can access the data you need to use mdadm and recover the array to a functional state. So add 2 drives with 2 TB more space then the rest, mirror the 2TB and add them to your vg. I wonder if anybody has more insight on this: do you think conceptually that BTRFS is similar in stability / robustness as MDADM or are there significant differences that should really take into account? tried moving the data from LVM to a physical disk by running ddrescue /dev/vg_sdi_sdj/all /dev/sdl1 - it seemed to work minus damaged data somewhere in the middle of disk. I wanted to migrate this PC to a virtual machine, so I booted both, the PC and the VM, with Clonezilla and cloned both disks into two separate disk images on the VM. They are both great, but I would personally consider BTRFS since it's in-kernel and ZFS supports RAID5/6, making it the better option in that scenario. LVM PV --dataalignment; The LVM offset is usually 1 MiB as well, check with pvs -o +pe_start. Custom storage layouts in 3. I have an existing LVM, with one physical drive (say /dev/sdb), and one volume group (say volgrp1), here I have three logical volumes (say lvSys, lvHome, lvSwap). In other words, mdadm RAID10 with 6 disks (I understand this to be spanned over 3 2-disk mirrors), If you're using LVM on top of mdadm, sometimes LVM will not delete the Device Mapper devices when deactivating the volume group. You can split every hdd in two equal partitions, group one partition per hdd in 6 hdd sets in two raid6 mdadm volumes and then make a raid1 btrfs from this In linux mdadm man page I saw the option "--write-journal". I have an mdadm RAID 1 with an LVM PV on top. Luks2 on top of RAID5 not mounting correctly. The up side to using lvm this way is that it does make expanding easy and the new drives don't have to be the same size. All of my issues came before even trying to select or create a file system. Now I worry about my data and by a second drive, completely identical to /dev/sdb and I want to create a mirrored device, that holds identical data to /dev/sdb but I want to keep all data while creating it. 04 LTS Server with two 3TB Fujitsu SATA disks with MBR partition tables. I do note that in my "real world" configurations I tend to run root directly on the RAID1 rather than on an LVM partition, but as a relatively small You probably have LVM on top of RAID. There are two ways LVM providing redundancy: block mirroring lvcreate -m 1 --mirrorlog mirrored -n . Both the md0 and dm-0 have settings of 4096 for RA, far higher than the block well an raid1 btrfs on top of raid6 mdadm splited in two can be a solution. like specifying the metadata version for mdadm arrays, etc? what about partitioning options, such as How to convert LVM on MDADM RAID1 on two MBR partitioned drives to GPT without data loss. Once the data has copied over, you can simply add the remaining disk by running mdadm --add /dev/md0 /dev/sdc1. But it also allows me to remove one mdadm array later, as long as the remaining mdadm array has enough free space for the data to be migrated. Virtual partitions allow addition and removal without worry Both. About 3-4 years ago, I switched most of my storage to Btrfs, using the filesystem’s built-in RAID1 mode. I'm having trouble installing a GRUB-booted system with mdadm RAID 1 on all partitions except "boot" (second partition) and LVM for the ROOT fs (LVM on top of mdadm RAID 1). If it is, consider ZFS. This makes it a bit cheaper to upgrade the array size, 8 drives to replace instead of 16. I have a RAID10 managed by the mdadm and I have EXT4 filesystem on top of it. 10 system was installed on a LVM setup on top of a mdadm RAID1 with 2x 500Gb disks for fault tolerance. Output from fdisk -l and lsblk is shown below : sudo fdisk -l /dev/sd[ab] Disk /dev/sda: 2,7 TiB, 3000592982016 bytes, 5860533168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 I have seen a few descriptions about using mdadm with lvm to create an easily expandable raid, such as this question, but I still think I'm missing something. Now that LVM supports RAID out of the box, it seems preferable (due to the flexibility offered) to rather use the RAID-support in LVM, but I suppose mdadm (or hardware RAID) is still needed for a bootable This means you can't use LUKS "on top of" Btrfs. For whatever reasons I need to replan this system/storage structure from scratch which means to copy out the whole system, wipe the whole LVM+mdadm RAID, set it up afresh and copy back the whole system, so I would do something like: I have no experience using LVM and in my experience, md raid6 has been pretty stable and safe over the years, so I'm considering adding it as a disk space allocation flexibility layer between my file systems and my md raid, but for flexibility only, because. On top of it, you have a few LVM volumes, and LUKS encrypted partitions. You can most likely just sgdisk --zap the device, and then recreate the RAID with e. Ensure there's nothing in the output of sudo vgdisplay. Assuming I want to use bcache for caching, mdadm for RAID (1) and LVM for partitioning (and that I don't care that there might be performance drawbacks due to many levels of I/O and device management introduced) what would be the best hierarchy on top of the physical device? Can mdadm work with bcache devices and eventual failures of both backing We rented a server with two NVMe disks in a raid1 configuration with a lvm on top of that. The best thing I ever did was ditch hardware RAID (various Dell controllers). By the way, if this happens to you, your data is not lost. LVM leverages the existing mdadm (RAID) capabilities in the kernel to do RAID-style redundancy without the need for using mdadm to separately to administer a RAID. conf. When you increase the effective disk space at the physical layer you just need to update the available space in order, layer by layer. Hardware RAID, software RAID, SAN, etc. "mdadm failed to add /dev/sdl1 to /dev/md1: Invalid argument" - nothing in the logs. Now instead of using a real device or real partition here we are going to use loop devices. To discover how bad they can be, simply append --sync=1 to your fio command (short story: they are incredibly bad, at least when compared to proper BBU RAID controllers or powerloss-protected SSDs);. It has been running strong for the last 10 years, with the occasional disk replaced. However, LVM can create logical volumes that are backed by a software RAID. More posts you may like I run LVM on LUKS on mdadm (RAID 6). It contains a volume group and is divided into several data partitions. Ask Question Asked 5 and I formatted /dev/mapper/crypt0 as an lvm physical volume, on which I put volume group vg1. (Often LVM on top of LUKS on top of RAID. What is the LVM log for Skip to main content. Then I still need a file system anyway, so instead of sticking plain old EXT4 on it, why not use BTRFS, and have that do snapshots? Synology uses, as far as I am aware, the Btrfs file system on top of mdadm RAID. › Configuring LVM on top of RAID : Let's mannualy i am goint to fail partition /dev/sda8 for testing purpose to see the result of it's effect on raid and lvm. So to allow for caching, I figured just stick LVM on top of the MD array. It technically works, but completely defeats the point of almost everything involved. Regardless of using RAID or plain disks, lvm allows much more flexibility in allocating that space. The VG on top of md2 has 4 LVs, var, home, usr, tmp. 37) to create an md device, then use LVM to provide volume management on top of the device, and then use ext4 as our filesystem on the LVM volume groups. mdadm -E can read the superblock but doesn't want to add the drive to array. LVM is created on top of the RAID device and volumes are then created in it, to provide partitions. I run a LVM setup on a raid1 created by mdadm. The probe command does not work at all on either (hd1,gpt1) or (md/linux); it just says error: unknown filesystem. My problem is that after reboot, although /dev/md0 does exist, and mdadm -Ds shows the appropriate information, and the crypt volume /dev/mapper/crypt0 also exists I would not mix md (software RAID) and md (LVM) RAID features. You can use LVM to manage your MD array depending on what you want to do it may or may not cover everything. If you just want to snapshot your root partition and get the benefits of deduping, then BTRFS on your LVM should work just fine. Recent versions of lvm implements RAID using the mdraid back end so it's not going to be substantially different on disk. All works fine. If you need data encryption, the other options are: Set up an ZFS array, as ZFS now has data encryption integrated without needing LUKS. RAID5 has an inherent write I use LVM on top of RAID extensively. mdadm can also do raid10, sacrificing space for redundancy so you can have a drive fail and still work without it. Modified 3 years, 9 months ago. Home › Archives › Configuring LVM on top of RAID : An alternative way to partitioning RAID Devices. MDADM/MDRAID with LVM and BTRFS? Something like how Synology has this implemented would be awesome! mathew2214 October 14, 2020, 2:59pm something like RAID 1 or RAID 10 under the hood then at install time that block storage is presented to the OS to use LVM on top of. My hope was to use software raid to create md0, use md0 as a PV for LVM, then use LVM to create a volume group (probably just one) and logical volumes for the shares. Starting with two completely blank and erased disks (no file system at all), I was able to create the array (md0) using MDADM, but then I couldn't use that array as the basis for a physical volume in LVM. Logical Volume Management utilizes the kernel's device-mapper feature to provide a system of partitions independent of underlying disk layout. apt install mdadm If you get a dns error, do. Configure LVM on top of the encrypted layers Create the physical We use RAID1+0 with md on Linux (currently 2. I tried running mdadm --grow /dev/md4 -l 0 but got an error: mdadm: failed to remove internal bitmap. Look in /dev/mapper/. You can delete it manually. I never had any issue with MDADM reliability. You can add your existing mdadm device as LVM physical volume, without having it to re-sync the raid. [root@test64 laytonjb]# mdadm --create --verbose /dev/md0 --level raid0 --raid-devices=2 /dev/sdb1 /dev/sdc1 The “chunk size”, or stripe width, defaults to 64KB. ATM my MDADM array is mounted to one place without LVM on top of it. But a couple of years ago, you had to stack LVM on mdadm devices in order to get RAID5 redundancy (striping+parity). Note that LVM is capable of striping data, but so is mdadm. there is no extra /boot partition (the system will directly boot from the lvm which is on top of the mdadm); this works since grub2; this setup is pretty similar to using fdisk (MBR) partitions; this guide still uses BIOS to boot (no EFI/UEFI) /dev/sda1 and /dev/sdb1 are very small partitions (2Mib); they are used to store the grub2 boot stages By combining mdadm with LVM, you can duplicate cache devices and do most of the things bcache does. I've shared the root folder via Samba, but there are also numerous subdirectories shared via Samba / NFS. With Fedora everything is recognized at boot. It gives you exactly as much space as RAID 10, but with much, much worse performance (you have to calculate two parities and face read-modify-write penalty for writes smaller than stripe size). If it isn't RAID5/6 then take a look at BTRFS. Create LVM on Top of RAID 5 The advantage of Logical Volume Management is that it will allow you to expand your partitions and allow you to take snapshots or backups of working partitions. I would have then formatted the logical volumes with BTRFS. If the superblock is at the start, mdadm uses a data offset that will be multiple of MiB (up to 128 MiB). What I would like to know, is what exactly is the fault tolerance in terms of a potential disk failure given it is RAID10, but with LVM running on-top of the software/mdadm RAID. To discover how bad they can be, simply append --sync=1 to your fio command (short story: @nh2 gives an easy but possibly dangerous solution in his answer to What's the difference between creating mdadm array using partitions or the whole disks directly. md2 is partition 9:2. I have an Ubuntu 18. You always want LVM, no matter what else is going on. conf ; Simple examples: lvm. Got lvm setup and a couple of volumes created with filesystems on top of md0 Made sure everything looked good, and rebooted. ). Check the data offset with mdadm --examine /dev/sda1. I tried to use LVM on top of a RAID 5 array and it failed. You just bought new 8Tb disks. 04 CLICK HERE. Tip: LVM itself supports logical volumes in RAID Building a RAID array using mdadm – two primary steps: Simple examples: ARRAY /dev/md/0 metadata=1. conf and repeat. Shares. It should contain a line near the end similar to To use the following. The reason I've opted to use lvm on top of standard mdraid is because you can't use mdadm on an lvm raid array and mdadm gives more visibility and function. My current set up is 2 mdadm raids over 6 SSDs; one on the first partition of each ssd (raid1) for /boot, the other mdadm raid is a raid10 on the second partition of each ssd that contains my LVM. mdadm raid is better for raid1 and on top of that you can put lvm for flexibility. I am talking software RAID here. How does this relate to lvmcache as lvmcache is built on top of dm-cache? Are they different things or does lvmcache do something like "-- On reflection I think it was my fault: instead of creating just one RAID 1 device (sda1 and sdb1) with LVM on top, I should have created two -- a small RAID 1 device for /boot (sda1 and sdb1 to make md0) and a second RAID 1 device (sda2 and sdb2 to make md1) for the LVM volume (with lvroot, lvswap, lvusr, lvvar, lvhome, etc. echo "nameserver 1. That all sounds good. Steps for LVM-on-crypt. That must be it. With 4 disks going RAID6 is a Bad Idea (TM). 7 TiB, 4000787030016 bytes, 7814037168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk /dev/sdb: 3. Say that I create the raid using mdadm with 4 drives using raid5, then make an lvm volume(?) on top of that, then format that lvm volume with ext3. Use the man pages for mdadm to identify how to recover the array. 1" >> /etc/resolv. You should check that one out as well. If the superblock is at the end, the alignment is the partition itself. An 8 disk RAID 6 array should be able to lose 2 devices and still function in a degraded state. The software RAID seems to be running ok, it is assemble from the following mdadm. I don't see how any snapshots at blocks level could be efficient in regard with disk space, compared to snapshots root@openmediavault:~# fdisk -l Disk /dev/sda: 3. For an example with BTRFS, I can't easily see the status when I remove/add another disk to the array like I can with mdadm (or The issue was trying to put LVM on top of an MDADM array. You literally set this up 10 years ago - 4 disks 2 Tb each. I own a Linux setup in a couple of mdadm mirrored (RAID 1) disks with LVM2 on the top. However, LVM can create logical My Ubuntu 8. 7 TiB, 4000787030016 bytes, 7814037168 sectors Units: sectors of 1 * 512 = 512 bytes mdadm uses the special keyword "missing" in place of a device name to create/manage degraded arrays. Those messages are from layers below mdadm. The raid array failed due to losing disks. g. [root@satish ~]# mdadm /dev/md5 --fail /dev/sda8 mdadm: Im not sure how mdadm raid would be faster than LVM in a --mirrors=1 assuming you're talking about mdadm RAID1 mirror since its just mirroring and, as I recall, for a mirror operation the controller (software or hardware) will not block an IO operation waiting for the primary to mirror to the secondary; although I could be wrong. apt install mdadm You may ignore any warnings about pipe leaks. With LVM you abstract your storage and have "virtual partitions", making extending/shrinking easier (subject to potential filesystem limitations). With LVM and Raid there are two ways available: LVM built in raid, and LVM on top of mdadm. In the spirit of KISS, I'd go with pure md with LVM on top for snapshots / resizes. Then after The system used a software RAID5 system on top of which an LVM was setup with a single partition of about 2. I already previously posted my article about speeding up Btrfs RAID 1 up using LVM cache. Use regular mdadm (or dm-raid, or LVM) to create the RAID array, put LUKS on top of that, then use Ext4 or XFS in that LUKS volume. 1. Output from fdisk -l and lsblk is shown below : For the first 12 years of them, I’ve been using ext3/4 on top of mdadm managed RAID1. Use RAID for the RAID portion and LVM for the logical volume management. Can RS RAID Retrieve rebuild my RAID 5 Or maybe I made the mirror with mdadm and put LVM on top. Install mdadm. You probably have LVM on top of RAID. It's well-known that mdadm won't let you --grow raid10, my question is whether this is a limitation of LVM RAID10 too? If it is possible, what are the downsides of LVM RAID10 versus LVM on top of md RAID10? “mdadm –create” to build the array using available resources “mdadm –detail –scan” to build config string for /etc/mdadm/mdadm. So it's not capable of identifying the MD-raid, let alone the LVM stuff, even though GRUB is already accessing the MD-raid. Aside from the control file, I have an old PC which has two internal hard drives of 80GB in a mdadm RAID1 configuration with LVM on top of it. The pv size (of RAID1) is unchanged by losing 1 device, so LVM carries on regardless. We don't need redundancy but might need more disk space soon. You can also use mdadm to handle the raid parts, then stack LVM on top of it if you wish, just to carve up the space into volumes and add abilities like snapshots. reason being we are suddenly having odd issues with a kernel with raid10+lvm on top and mainly as any change in the structure or sizes of the The bad recorded performances stem from different factors: mechanical disks are simply very bad at random read/write IO. On the other hand, a 4 disk mdadm raid10 configured to use the offset striping mode can give seqential read performance near that of a 4 disk raid0, but an lvm stripe on top of two mdadm raid1s only has the performance of two disks. This is the way it We know mdadm is very solid but LVM provides great flexibility in order to move live partitions from one disk to other, replace one of the disks and specially extending or reducing partitions. New datacenter deployment using Maas questions. . Stack Exchange Network. First, it seems like the VM loads the bootloader, but then stops But it did not find any of the LVM devices I had created, which should have looked like (lvm/vg_linux/lv_root). I then tried to introduce LVM into the mix. 3 and RAID10 as of 6. Some additional info: But when I create a LUKS container on top of the mdadm device, I get terrible performance: To recap: That includes LVM spanning, striping, and mirroring. Does anyone know of a guide to configuring LVM on top of mdadm RAID 1? I set this up on Slackware current a couple of days ago and had an issue when trying to reconfigure lilo. md2 is based on sda6 (major:minor 8:6) and sdb6 (8:22). So instead of having 16 drives in one mdadm array, I can have two mdadm arrays with 8 drives. Viewed 302 times 2 . With SSDs as the drives, we'd like to see the TRIM commands propagate through the layers (ext4 -> LVM -> md -> SSD) to the devices. Physical; RAID; LUKS; PV for VG/LVM; If you get the order of operations wrong nothing bad will happen - you'll just get no change. I never really used btrfs but i can tell you that at least with lvm on top of mdadm you could later create something like synologys shr. 2 spares=1 name=debian6-vm:0 The following tutorial is intended to walk you through configuring a RAID 1 mirror using two drives with Mdadm and then configuring LVM on top of that mirror with the XFS file system. The Does anyone know of a guide to configuring LVM on top of mdadm RAID 1? I set this up on Slackware current a couple of days ago and had an issue when trying to reconfigure Lvm and mdadm are two similar and at the same time completely different utilities designed to handle disk information. If say, you need to set up different passwords for different LVs, you definitely need to put LUKS on top of LVM. 6. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. So when you create the array, you would run mdadm --create /dev/md0 --level=10 --raid-devices=4 /dev/sdd1 /dev/sde1 /dev/sdf1 missing. LVM did NOT come up, because the array did not reassemble. Installation from LiveCD seems to complete with no glitches, but on booting from HDD the root partition is not found. For information on creating Logical Volumes on Ubuntu 8. After the reboot it fail to start and I get recovery The bad recorded performances stem from different factors: mechanical disks are simply very bad at random read/write IO. The key trick with LVM is the kernel can manage turning things on and off even without rebooting, and a hard crash means the backing device at least has some/most data on it without its cache drive being alive. Second variant offers more flexibility in some situations. Instead of using the device name, use the /dev/mapper paths for each of the disks to create a physical volume (on the crypt layer on top of the disk, not on the disk itself). You can do RAID 1 via LVM but I’d recommend letting the MDADM RAID subsystem handle that and keep LVM on top of. As you all know that once we have created LVM on top of RAID, it become so easy to add any other volume to RAID. # pvcreate /dev/md4 Create the physical volume out of your RAID array. conf, Your LVM is built on top of mdadm - LVM neither knows nor cares of the physical devices; it cares about /dev/md[012]. I have no experience with mdadm. HostRAID. Creating mdadm arrays on top of an LVM logical volume is nonsense. Now that the underlying disks are encrypted, you can create the LVM structures. Then after You have a linux software raid (raid5, in my case, created with mdadm). After finalizing the LVM [root@test64 laytonjb]# mdadm --create --verbose /dev/md0 --level raid0 --raid-devices=2 /dev/sdb1 /dev/sdc1 The “chunk size”, or stripe width, defaults to 64KB. Inspect the configuration file /etc/mdadm/mdadm. This is a bit more difficult in LVM since it is different than RAID. RHEL LVM has supported RAID4/5/6 as of 6. Lvm has problems when a disk goes bad, mdadm is the tried and proved solution for raid1. Background LVM building blocks. mdadm on the top of LVM doesn't make much sense, but LVM on the top of mdadm was considered "best practice" when not having a hardware raid. My understanding is this is basically what synology does in their software. Software RAID in Linux is implemented through the md Multiple Devices device driver, and mdadmis the tool to administer these RAID See more Is it more recommended to use LVM on top of mdadm for logical volume management, or is it fine to let LVM manage the raid as well? Is it even considerable to use This article will provide an example of how to install and configure Arch Linux with Logical Volume Manager (LVM) on top of a software RAID. The consistency, flexibility, control, features, and lack of vendor lock-in make it a no brainier. I've got LVM logical volume on top of MDADM RAID1 setup. Best would be different models I would not mix md (software RAID) and md (LVM) RAID features. 4. Your LVM is built on top of mdadm - LVM neither knows nor cares of the physical devices; it cares about /dev/md[012]. So, lot of people still do it that way—stacking LVM on RAID—even though it's no longer required. Ask Question Asked 3 years, 9 months ago. As you know, with RAID1 you lose one of the disks for First, the order of LUKS and LVM depends on if you want to have different LUKS passwords or other settings for different LVs. 1? Debugging node storage without commissioning. Virtual partitions allow addition and removal without worry My main file server storage (running Ubuntu) is currently managed by mdadm (16 2TB spinning drives in raid10). 5 TB size for a mount like /data. To contrast RAID-0 and LVM they need to be constructed as similarly as possible. ) More recently I've been trying ZFS, but before I put that into heavy use I need to see the encryption layer working. Likewise filesystem UUIDs are not dependent on adding new device(s) to the array. Motherboards may provide some RAID mode but on consumer and entry-level boards this is typically software RAID in disguise, e. However, I like BTRFS and would like to convert the EXT4 filesystem to BTRFS, but I was thinking about performance and maintainability. Doesn't matter. shbh bcuodf kvx jjtln flwgazc rdxzaa gld bexp ynsuhcdf rxvmyq