Adding wiki for Backup storage domain #1003
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| title: BackupStorageDomain | ||
| category: feature | ||
| authors: mlipchuk, shubham0d | ||
| feature_name: Backup Storage Domain | ||
| feature_modules: engine/vdsm | ||
| feature_status: Yet to Impelement | ||
| --- | ||
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| # Backup Storage Domain | ||
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| This feature will add another functionality layer to the oVirt Disaster Recovery solution. It will allow any data storage domain to use as a backup domain and hence will remove the limitations of export storage domain. Adding functionality of backup storage domain deprecate the use of export storage domain and in future may replace it. | ||
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| ## Owner | ||
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| * Maor Lipchuk <mlipchuk@redhat.com> | ||
| * Shubham Dubey <sdubey504@gmail.com> | ||
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| ## Current status | ||
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| * Implemented | ||
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| ## Summary | ||
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| Until now, one of the solutions to backup VMs and Templates in oVirt was to use an export storage domain. | ||
| Export storage domain is a dedicated storage domain which is used to store and restore VMs and Templates. | ||
| The drawback of Export storage domain is its two stage process. Transferring a VM required first copying it into the export storage domain and then into other storage domain to start using them. Since in background transfer from one domain to other take place using normal copy or dd utility (in case of disks) this process take a large time for a complete transfer. Hence, for a better backup experience we decided to create a whole dedicated storage domain to be used only for backup which obviously will call as backup storage domain. | ||
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| ## GSOC | ||
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| This feature is being developed as part of the Google Summer of Code [GSOC](https://developers.google.com/open-source/gsoc/). | ||
| Google Summer of Code is a global program focused on introducing students to open source software | ||
| development. Students work on a 3 month programming project with an open source organization | ||
| during their break from university.<br /> | ||
| The oVirt organization has chosen Shubham Dubey, a student from The LNM Institute of Information Technology from India, to work on this project for the upcoming summer and Maor Lipchuk, a senior software developer in the oVirt storage team, to be the mentor. | ||
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| ## Backup Storage Domain - Functionality | ||
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| * You can select any data storage domain as backup storage. | ||
| * Once the storage domain is configured as backup the engine will block any running VMs or any other action that may invalidate the backup which might be in the storage domain. | ||
| * A backup storage domain can be detached and attached to a data center as every data storage domain. | ||
| * The backup indication will only be configured using the DataBase and will not be configured in the storage domain metadata - The user will be able to configure a storage domain as backup once a data storage domain is being imported or added to oVirt. | ||
| * There is no obligation regarding data center version in oVirt to a backup storage domain. A backup storage domain can be part of every Data Center version. | ||
| * A user can run a VM based on a Template which one of its disks is part of a backup storage domain while all the VM's disks are not part of the backup storage domain. | ||
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| #### Advantages | ||
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| * Much more dedicated storage domain for backup and disaster recovery purposes. | ||
| * One step process-If you want a backup of VM/Template then just transfer it to backup storage domain. | ||
| * For huge amount of VMs/Templates and OVFs migration the time taken for copying through export will be high which will be minimized by using backup storage domain. | ||
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There was a problem hiding this comment. The point that needs to be made here is that a backup domain can just be truned into a regular data domain at any instant. |
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| * Large amount of extra space is used in export storage domain. It may be suitable for small datacenter but for large datacenter the storage required to store those OVFs and VMs in export storage domain will become a headache. | ||
| * Multiple storage domain can be used for backup purposes only. | ||
| * Backup storage domain will support both File storage(NFS , Gluster) as well as block storage(Fiber Channel and iSCSI) as compared to export storage domain which only has support for file storage. | ||
| * A backup storage domain can be truned into a regular data domain at any instant and vise versa. | ||
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| #### Restrictions | ||
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| * A data storage domain can not be configured as backup while there are VMs that are not down, paused, hibernate etc with disks residing on that storage domain. | ||
| * User can not run VMs with disks residing on a storage domain configured as backup, since running VM might manipulate the disk's data. | ||
| * VMs with disks residing on a backup storage domain can not be previewed. | ||
| * Live move of disks to the backup storage domain will be restricted. | ||
| * A backup domain cannot be elected as the master domain. | ||
| * The Hosted Engine's domain can't be configured as a backup domain. | ||
| * The backup domain cannot be the target of memory volumes since memory volume is only supported for running VMs and those are not allowed on backup storage domains. | ||
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| #### Open Issues | ||
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| * Preview will be restricted for VMs with disks residing on a backup storage. - We think it should be restricted since currently oVirt does not support import storage domain with previewed unregistered entities. | ||
| * Shared disk will be restricted in the backup storage domain since those are not specified in the VM's OVF. | ||
| * VM pool will be eligible in a backup storage domain although, the user must keep in mind that import storage domain will not preserve its pool reference after import. | ||
| * Should the backup indication need to be configured in the storage domain meta data? If so should we add the backup indication as part of V4 storage domain meta data. | ||
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| ## Phases for Implementation | ||
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| - [x] Phase 1 (under review): Add dal layer with new field - | ||
| * introducing new field 'backup' in table storage_domain_static | ||
| * Add field changes in fixtures.xml for dao tests | ||
| * Test class added for dao test | ||
| - [x] Phase 2: Added command validations for configuring backup storage domain - [see restrictions] | ||
| - [x] Phase 3: Added REST Api request and webadmin checkbox to update storage domain as backup | ||
| * Introduce the ability to update the storage domain as backup through REST and web based GUI. | ||
| * Implemented GUI checkbox below wipe after delete for backup flag in import domain dialog and add storage domain dialog. | ||
| * REST request for setting backup flag on storage domain by passing backup true or false.This flag can be used while creating a domain or importing a domain. | ||
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| ## Future plans | ||
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| * Adding a tool that can convert export storage domain into data domain.So that user that have export storage domain in their engine can convert them into data domain before we totally get rid of export storage domain. | ||
| * Convert Export storage domain to backup domain - This backup feature can be a good replacement for export storage domain. So,if community agree then we will remove the export storage domain and replace it with the backup storage domain. | ||
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| ## GUI Mockups | ||
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| An Import storage domain (NFS, iSCSI) screen: | ||
|  | ||
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| An Add New Storage Domain (NFS, iSCSI) screen: | ||
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| ## REST Requests | ||
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| ### Import block Storage Domain | ||
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There was a problem hiding this comment. What do any of these have to do with this feature? There was a problem hiding this comment. if you are talking about GUI mockups and REST requests then they are basically for demonstration purpose so reader will know how this feature can be used. But I can remove them if they are not necessary. |
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| #### Discover the targets in your iSCSI Storage Server | ||
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| ```xml | ||
| POST /api/hosts/052a880a-53e0-4fe3-9ed5-01f939d1df66/iscsidiscover | ||
| Accept: application/xml | ||
| Content-Type: application/xml | ||
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| <action> | ||
| <iscsi> | ||
| <address>iscsi.server</address> | ||
| </iscsi> | ||
| <iscsi_target>iqn.iscsi.120.01</iscsi_target> | ||
| <iscsi_target>iqn.iscsi.120.02</iscsi_target> | ||
| <iscsi_target>iqn.iscsi.120.03</iscsi_target> | ||
| </action> | ||
| ``` | ||
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| #### Get a candidates Storage Domains list to be imported | ||
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| After the iscsilogin operation, the host is already connected to the targets in the iSCSI and we can fetch the Storage Domains which are candidates to be imported. | ||
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| ```xml | ||
| POST /api/hosts/052a880a-53e0-4fe3-9ed5-01f939d1df66/unregisteredstoragedomainsdiscover HTTP/1.1 | ||
| Accept: application/xml | ||
| Content-type: application/xml | ||
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| <action> | ||
| <iscsi> | ||
| <address>iscsiHost</address> | ||
| </iscsi> | ||
| <iscsi_target>iqn.name1.120.01</iscsi_target> | ||
| <iscsi_target>iqn.name2.120.02</iscsi_target> | ||
| <iscsi_target>iqn.name3.120.03</iscsi_target> | ||
| </action> | ||
| ``` | ||
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| The response which should returned as a list of Storage Domains, as follows: | ||
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| ```xml | ||
| <action> | ||
| <iscsi> | ||
| <address>iscsiHost</address> | ||
| </iscsi> | ||
| <storage_domains> | ||
| <storage_domain id="6ab65b16-0f03-4b93-85a7-5bc3b8d52be0"> | ||
| <name>scsi4</name> | ||
| <type>data</type> | ||
| <backup>true</backup> | ||
| <master>false</master> | ||
| <storage> | ||
| <type>iscsi</type> | ||
| <volume_group id="OLkKwa-VmEM-abW7-hPiv-BGrw-sQ2E-vTdAy1"/> | ||
| </storage> | ||
| <available>0</available> | ||
| <used>0</used> | ||
| <committed>0</committed> | ||
| <storage_format>v3</storage_format> | ||
| </storage_domain> | ||
| <status> | ||
| <state>complete</state> | ||
| </status> | ||
| <iscsi_target>iqn.name1.120.01</iscsi_target> | ||
| <iscsi_target>iqn.name2.120.02</iscsi_target> | ||
| <iscsi_target>iqn.name3.120.03</iscsi_target> | ||
| </action> | ||
| ``` | ||
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| #### Import the iSCSI Storage Domains to the setup | ||
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| ```xml | ||
| POST /api/storagedomains/ HTTP/1.1 | ||
| Accept: application/xml | ||
| Content-type: application/xml | ||
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| <storage_domain id="39baf524-380e-407c-8625-50709fcaa9c2"> | ||
| <import>true</import> | ||
| <host id="052a880a-53e0-4fe3-9ed5-01f939d1df66" /> | ||
| <type>data</type> | ||
| <backup>true</backup> | ||
| <storage> | ||
| <type>iscsi</type> | ||
| </storage> | ||
| </storage_domain> | ||
| ``` | ||
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| #### Import the FCP Storage Domains to the setup | ||
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| ```xml | ||
| POST /api/storagedomains/ HTTP/1.1 | ||
| Accept: application/xml | ||
| Content-type: application/xml | ||
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| <storage_domain id="ecf053fc-fe65-4d64-883e-c38ca898951c"> | ||
| <import>true</import> | ||
| <host id="9d05868b-d40d-4a8c-9a81-dbf09d654fba" /> | ||
| <type>data</type> | ||
| <backup>true</backup> | ||
| <storage> | ||
| <type>fcp</type> | ||
| </storage> | ||
| </storage_domain> | ||
| ``` | ||
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| #### Import NFS Storage Domain | ||
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| Importing a Storage Domain requires a POST request, with the storage domain representation included, sent to the URL of the storage domain collection. | ||
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| ```xml | ||
| POST /api/storagedomains HTTP/1.1 | ||
| Accept: application/xml | ||
| Content-type: application/xml | ||
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| <storage_domain> | ||
| <name>data1</name> | ||
| <type>data</type> | ||
| <backup>true</backup> | ||
| <host id="052a880a-53e0-4fe3-9ed5-01f939d1df66"/> | ||
| <storage> | ||
| <type>nfs</type> | ||
| <address>10.35.16.2</address> | ||
| <path>/export/images/rnd/maor/data9</path> | ||
| </storage> | ||
| </storage_domain> | ||
| ``` | ||
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| The API creates an NFS data storage domain called data1 with an export path of 10.35.16.2:/export/images/rnd/maor/data9 and sets access to the storage domain through the hypervisor host. | ||
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@shubham0d you should add yourself to the
data/authors.ymlfile too so your username renders nicely here.