{ "mode": "man", "parameter": "lvmvdo", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/lvmvdo/7/json", "generated": "2026-06-13T22:58:01Z", "sections": { "NAME": { "content": "lvmvdo — Support for Virtual Data Optimizer in LVM\n", "subsections": [] }, "DESCRIPTION": { "content": "VDO is software that provides inline block-level deduplication, compression, and thin provi‐\nsioning capabilities for primary storage.\n\nDeduplication is a technique for reducing the consumption of storage resources by eliminating\nmultiple copies of duplicate blocks. Compression takes the individual unique blocks and\nshrinks them. These reduced blocks are then efficiently packed together into physical blocks.\nThin provisioning manages the mapping from logical blocks presented by VDO to where the data\nhas actually been physically stored, and also eliminates any blocks of all zeroes.\n\nWith deduplication, instead of writing the same data more than once, VDO detects and records\neach duplicate block as a reference to the original block. VDO maintains a mapping from Logi‐\ncal Block Addresses (LBA) (used by the storage layer above VDO) to physical block addresses\n(used by the storage layer under VDO). After deduplication, multiple logical block addresses\nmay be mapped to the same physical block address; these are called shared blocks and are ref‐\nerence-counted by the software.\n\nWith compression, VDO compresses multiple blocks (or shared blocks) with the fast LZ4 algo‐\nrithm, and bins them together where possible so that multiple compressed blocks fit within a\n4 KB block on the underlying storage. Mapping from LBA is to a physical block address and in‐\ndex within it for the desired compressed data. All compressed blocks are individually refer‐\nence counted for correctness.\n\nBlock sharing and block compression are invisible to applications using the storage, which\nread and write blocks as they would if VDO were not present. When a shared block is overwrit‐\nten, a new physical block is allocated for storing the new block data to ensure that other\nlogical block addresses that are mapped to the shared physical block are not modified.\n\nTo use VDO with lvm(8), you must install the standard VDO user-space tools vdoformat(8) and\nthe currently non-standard kernel VDO module \"kvdo\".\n\nThe \"kvdo\" module implements fine-grained storage virtualization, thin provisioning, block\nsharing, and compression. The \"uds\" module provides memory-efficient duplicate identifica‐\ntion. The user-space tools include vdostats(8) for extracting statistics from VDO volumes.\n", "subsections": [] }, "VDO TERMS": { "content": "VDODataLV\nVDO data LV\nA large hidden LV with the vdata suffix. It is created in a VG\nused by the VDO kernel target to store all data and metadata blocks.\n\nVDOPoolLV\nVDO pool LV\nA pool for virtual VDOLV(s), which are the size of used VDODataLV.\nOnly a single VDOLV is currently supported.\n\nVDOLV\nVDO LV\nCreated from VDOPoolLV.\nAppears blank after creation.\n", "subsections": [] }, "VDO USAGE": { "content": "The primary methods for using VDO with lvm2:\n", "subsections": [ { "name": "1. Create a VDOPoolLV and a VDOLV", "content": "Create a VDOPoolLV that will hold VDO data, and a virtual size VDOLV that the user can use.\nIf you do not specify the virtual size, then the VDOLV is created with the maximum size that\nalways fits into data volume even if no deduplication or compression can happen (i.e. it can\nhold the incompressible content of /dev/urandom). If you do not specify the name of\nVDOPoolLV, it is taken from the sequence of vpool0, vpool1 ...\n\nNote: The performance of TRIM/Discard operations is slow for large volumes of VDO type.\nPlease try to avoid sending discard requests unless necessary because it might take consider‐\nable amount of time to finish the discard operation.\n" }, { "name": "lvcreate --type vdo -n VDOLV -L DataSize -V LargeVirtualSize VG/VDOPoolLV", "content": "" }, { "name": "lvcreate --vdo -L DataSize VG", "content": "Example\n# lvcreate --type vdo -n vdo0 -L 10G -V 100G vg/vdopool0\n# mkfs.ext4 -E nodiscard /dev/vg/vdo0\n" }, { "name": "2. Convert an existing LV into VDOPoolLV", "content": "Convert an already created or existing LV into a VDOPoolLV, which is a volume that can hold\ndata and metadata. You will be prompted to confirm such conversion because it IRREVERSIBLY\nDESTROYS the content of such volume and the volume is immediately formatted by vdoformat(8)\nas a VDO pool data volume. You can specify the virtual size of the VDOLV associated with this\nVDOPoolLV. If you do not specify the virtual size, it will be set to the maximum size that\ncan keep 100% incompressible data there.\n" }, { "name": "lvconvert --type vdo-pool -n VDOLV -V VirtualSize VG/VDOPoolLV", "content": "" }, { "name": "lvconvert --vdopool VG/VDOPoolLV", "content": "Example\n# lvconvert --type vdo-pool -n vdo0 -V10G vg/ExistingLV\n" }, { "name": "3. Change the default settings used for creating a VDOPoolLV", "content": "VDO allows to set a large variety of options. Lots of these settings can be specified in\nlvm.conf or profile settings. You can prepare a number of different profiles in the\n/etc/lvm/profile directory and just specify the profile file name. Check the output of lvm‐‐\nconfig --type full for a detailed description of all individual VDO settings.\n\nExample\n# cat < /etc/lvm/profile/vdocreate.profile\nallocation {\nvdousecompression=1\nvdousededuplication=1\nvdousemetadatahints=1\nvdominimumiosize=4096\nvdoblockmapcachesizemb=128\nvdoblockmapperiod=16380\nvdocheckpointfrequency=0\nvdousesparseindex=0\nvdoindexmemorysizemb=256\nvdoslabsizemb=2048\nvdoackthreads=1\nvdobiothreads=1\nvdobiorotation=64\nvdocputhreads=2\nvdohashzonethreads=1\nvdologicalthreads=1\nvdophysicalthreads=1\nvdowritepolicy=\"auto\"\nvdomaxdiscard=1\n}\nEOF\n\n# lvcreate --vdo -L10G --metadataprofile vdocreate vg/vdopool0\n# lvcreate --vdo -L10G --config 'allocation/vdocputhreads=4' vg/vdopool1\n" }, { "name": "4. Change the compression and deduplication of a VDOPoolLV", "content": "Disable or enable the compression and deduplication for VDOPoolLV (the volume that maintains\nall VDO LV(s) associated with it).\n" }, { "name": "lvchange --compression [y|n] --deduplication [y|n] VG/VDOPoolLV", "content": "Example\n# lvchange --compression n vg/vdopool0\n# lvchange --deduplication y vg/vdopool1\n" }, { "name": "5. Checking the usage of VDOPoolLV", "content": "To quickly check how much data on a VDOPoolLV is already consumed, use lvs(8). The Data%\nfield reports how much data is occupied in the content of the virtual data for the VDOLV and\nhow much space is already consumed with all the data and metadata blocks in the VDOPoolLV.\nFor a detailed description, use the vdostats(8) command.\n\nNote: vdostats(8) currently understands only /dev/mapper device names.\n\nExample\n# lvcreate --type vdo -L10G -V20G -n vdo0 vg/vdopool0\n# mkfs.ext4 -E nodiscard /dev/vg/vdo0\n# lvs -a vg\n\nLV VG Attr LSize Pool Origin Data%\nvdo0 vg vwi-a-v--- 20.00g vdopool0 0.01\nvdopool0 vg dwi-ao---- 10.00g 30.16\n[vdopool0vdata] vg Dwi-ao---- 10.00g\n\n# vdostats --all /dev/mapper/vg-vdopool0-vpool\n/dev/mapper/vg-vdopool0 :\nversion : 30\nrelease version : 133524\ndata blocks used : 79\n...\n" }, { "name": "6. Extending the VDOPoolLV size", "content": "You can add more space to hold VDO data and metadata by extending the VDODataLV using the\ncommands lvresize(8) and lvextend(8). The extension needs to add at least one new VDO slab.\nYou can configure the slab size with the allocation/vdoslabsizemb setting.\n\nYou can also enable automatic size extension of a monitored VDOPoolLV with the activa‐‐\ntion/vdopoolautoextendpercent and activation/vdopoolautoextendthreshold settings.\n\nNote: You cannot reduce the size of a VDOPoolLV.\n\nNote: You cannot change the size of a cached VDOPoolLV.\n" }, { "name": "lvextend -L+AddingSize VG/VDOPoolLV", "content": "Example\n# lvextend -L+50G vg/vdopool0\n# lvresize -L300G vg/vdopool1\n" }, { "name": "7. Extending or reducing the VDOLV size", "content": "You can extend or reduce a virtual VDO LV as a standard LV with the lvresize(8), lvextend(8),\nand lvreduce(8) commands.\n\nNote: The reduction needs to process TRIM for reduced disk area to unmap used data blocks\nfrom the VDOPoolLV, which might take a long time.\n" }, { "name": "lvextend -L+AddingSize VG/VDOLV", "content": "" }, { "name": "lvreduce -L-ReducingSize VG/VDOLV", "content": "Example\n# lvextend -L+50G vg/vdo0\n# lvreduce -L-50G vg/vdo1\n# lvresize -L200G vg/vdo2\n" }, { "name": "8. Component activation of a VDODataLV", "content": "You can activate a VDODataLV separately as a component LV for examination purposes. The acti‐\nvation of the VDODataLV activates the data LV in read-only mode, and the data LV cannot be\nmodified. If the VDODataLV is active as a component, any upper LV using this volume CANNOT\nbe activated. You have to deactivate the VDODataLV first to continue to use the VDOPoolLV.\n\nExample\n# lvchange -ay vg/vpool0vdata\n# lvchange -an vg/vpool0vdata\n" } ] }, "VDO TOPICS": { "content": "", "subsections": [ { "name": "1. Stacking VDO", "content": "You can convert or stack a VDOPooLV with these currently supported volume types: linear,\nstripe, raid, and cache with cachepool.\n" }, { "name": "2. VDOPoolLV on top of raid", "content": "Using a raid type LV for a VDODataLV.\n\nExample\n# lvcreate --type raid1 -L 5G -n vdopool vg\n# lvconvert --type vdo-pool -V 10G vg/vdopool\n" }, { "name": "3. Caching a VDODataLV or a VDOPoolLV", "content": "VDODataLV (accepts also VDOPoolLV) caching provides a mechanism to accelerate reads and\nwrites of already compressed and deduplicated data blocks together with VDO metadata.\n\nA cached VDO data LV cannot be currently resized. Also, the threshold based automatic resize\nwill not work.\n\nExample\n# lvcreate --type vdo -L 5G -V 10G -n vdo1 vg/vdopool\n# lvcreate --type cache-pool -L 1G -n cachepool vg\n# lvconvert --cache --cachepool vg/cachepool vg/vdopool\n# lvconvert --uncache vg/vdopool\n" }, { "name": "4. Caching a VDOLV", "content": "VDO LV cache allow you to 'cache' a device for better performance before it hits the process‐\ning of the VDO Pool LV layer.\n\nExample\n# lvcreate --type vdo -L 5G -V 10G -n vdo1 vg/vdopool\n# lvcreate --type cache-pool -L 1G -n cachepool vg\n# lvconvert --cache --cachepool vg/cachepool vg/vdo1\n# lvconvert --uncache vg/vdo1\n" }, { "name": "5. Usage of Discard/TRIM with a VDOLV", "content": "You can discard data on a VDO LV and reduce used blocks on a VDOPoolLV. However, the current\nperformance of discard operations is still not optimal and takes a considerable amount of\ntime and CPU. Unless you really need it, you should avoid using discard.\n\nWhen a block device is going to be rewritten, its blocks will be automatically reused for new\ndata. Discard is useful in situations when user knows that the given portion of a VDO LV is\nnot going to be used and the discarded space can be used for block provisioning in other re‐\ngions of the VDO LV. For the same reason, you should avoid using mkfs with discard for a\nfreshly created VDO LV to save a lot of time that this operation would take otherwise as de‐\nvice is already expected to be empty.\n" }, { "name": "6. Memory usage", "content": "The VDO target requires 370 MiB of RAM plus an additional 268 MiB per each 1 TiB of physical\nstorage managed by the volume.\n\nUDS requires a minimum of 250 MiB of RAM, which is also the default amount that deduplication\nuses.\n\nThe memory required for the UDS index is determined by the index type and the required size\nof the deduplication window and is controlled by the allocation/vdousesparseindex setting.\n\nWith enabled UDS sparse indexing, it relies on the temporal locality of data and attempts to\nretain only the most relevant index entries in memory and can maintain a deduplication window\nthat is ten times larger than with dense while using the same amount of memory.\n\nAlthough the sparse index provides the greatest coverage, the dense index provides more dedu‐\nplication advice. For most workloads, given the same amount of memory, the difference in\ndeduplication rates between dense and sparse indexes is negligible.\n\nA dense index with 1 GiB of RAM maintains a 1 TiB deduplication window, while a sparse index\nwith 1 GiB of RAM maintains a 10 TiB deduplication window. In general, 1 GiB is sufficient\nfor 4 TiB of physical space with a dense index and 40 TiB with a sparse index.\n" }, { "name": "7. Storage space requirements", "content": "You can configure a VDOPoolLV to use up to 256 TiB of physical storage. Only a certain part\nof the physical storage is usable to store data. This section provides the calculations to\ndetermine the usable size of a VDO-managed volume.\n\nThe VDO target requires storage for two types of VDO metadata and for the UDS index:\n\n• The first type of VDO metadata uses approximately 1 MiB for each 4 GiB of physical\nstorage plus an additional 1 MiB per slab.\n\n• The second type of VDO metadata consumes approximately 1.25 MiB for each 1 GiB of log‐\nical storage, rounded up to the nearest slab.\n\n• The amount of storage required for the UDS index depends on the type of index and the\namount of RAM allocated to the index. For each 1 GiB of RAM, a dense UDS index uses 17\nGiB of storage and a sparse UDS index will use 170 GiB of storage.\n\n" } ] }, "SEE ALSO": { "content": "lvm(8), lvm.conf(5), lvmconfig(8), lvcreate(8), lvconvert(8), lvchange(8), lvextend(8), lvre‐‐\nduce(8), lvresize(8), lvremove(8), lvs(8), vdo(8), vdoformat(8), vdostats(8), mkfs(8)\n\n\n\nRed Hat, Inc LVM TOOLS 2.03.11(2) (2021-01-08) LVMVDO(7)", "subsections": [] } }, "summary": "lvmvdo — Support for Virtual Data Optimizer in LVM", "flags": [], "examples": [], "see_also": [ { "name": "lvm", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvm/8/json" }, { "name": "lvm.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/lvm.conf/5/json" }, { "name": "lvmconfig", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvmconfig/8/json" }, { "name": "lvcreate", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvcreate/8/json" }, { "name": "lvconvert", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvconvert/8/json" }, { "name": "lvchange", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvchange/8/json" }, { "name": "lvextend", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvextend/8/json" }, { "name": "duce", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/duce/8/json" }, { "name": "lvresize", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvresize/8/json" }, { "name": "lvremove", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvremove/8/json" }, { "name": "lvs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/lvs/8/json" }, { "name": "vdo", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/vdo/8/json" }, { "name": "vdoformat", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/vdoformat/8/json" }, { "name": "vdostats", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/vdostats/8/json" }, { "name": "mkfs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/mkfs/8/json" } ] }