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b1f48b2a | 1 | [[chapter_pvesr]] |
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2 | ifdef::manvolnum[] |
3 | pvesr(1) | |
4 | ======== | |
5 | :pve-toplevel: | |
6 | ||
7 | NAME | |
8 | ---- | |
9 | ||
236bec37 | 10 | pvesr - Proxmox VE Storage Replication |
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11 | |
12 | SYNOPSIS | |
13 | -------- | |
14 | ||
15 | include::pvesr.1-synopsis.adoc[] | |
16 | ||
17 | DESCRIPTION | |
18 | ----------- | |
19 | endif::manvolnum[] | |
20 | ||
21 | ifndef::manvolnum[] | |
22 | Storage Replication | |
23 | =================== | |
24 | :pve-toplevel: | |
25 | endif::manvolnum[] | |
26 | ||
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27 | The `pvesr` command line tool manages the {PVE} storage replication |
28 | framework. Storage replication brings redundancy for guests using | |
728a3ea5 | 29 | local storage and reduces migration time. |
45c218cf | 30 | |
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31 | It replicates guest volumes to another node so that all data is available |
32 | without using shared storage. Replication uses snapshots to minimize traffic | |
33 | sent over the network. Therefore, new data is sent only incrementally after | |
c93fb4bf | 34 | the initial full sync. In the case of a node failure, your guest data is |
728a3ea5 | 35 | still available on the replicated node. |
236bec37 | 36 | |
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37 | The replication is done automatically in configurable intervals. |
38 | The minimum replication interval is one minute, and the maximal interval | |
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39 | once a week. The format used to specify those intervals is a subset of |
40 | `systemd` calendar events, see | |
41 | xref:pvesr_schedule_time_format[Schedule Format] section: | |
236bec37 | 42 | |
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43 | It is possible to replicate a guest to multiple target nodes, |
44 | but not twice to the same target node. | |
236bec37 | 45 | |
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46 | Each replications bandwidth can be limited, to avoid overloading a storage |
47 | or server. | |
236bec37 | 48 | |
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49 | Only changes since the last replication (so-called `deltas`) need to be |
50 | transferred if the guest is migrated to a node to which it already is | |
51 | replicated. This reduces the time needed significantly. The replication | |
52 | direction automatically switches if you migrate a guest to the replication | |
53 | target node. | |
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54 | |
55 | For example: VM100 is currently on `nodeA` and gets replicated to `nodeB`. | |
56 | You migrate it to `nodeB`, so now it gets automatically replicated back from | |
57 | `nodeB` to `nodeA`. | |
58 | ||
59 | If you migrate to a node where the guest is not replicated, the whole disk | |
c93fb4bf | 60 | data must send over. After the migration, the replication job continues to |
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61 | replicate this guest to the configured nodes. |
62 | ||
63 | [IMPORTANT] | |
64 | ==== | |
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65 | High-Availability is allowed in combination with storage replication, but there |
66 | may be some data loss between the last synced time and the time a node failed. | |
728a3ea5 | 67 | ==== |
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68 | |
69 | Supported Storage Types | |
70 | ----------------------- | |
71 | ||
72 | .Storage Types | |
73 | [width="100%",options="header"] | |
74 | |============================================ | |
75 | |Description |PVE type |Snapshots|Stable | |
76 | |ZFS (local) |zfspool |yes |yes | |
77 | |============================================ | |
78 | ||
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79 | [[pvesr_schedule_time_format]] |
80 | Schedule Format | |
81 | --------------- | |
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82 | Replication uses xref:chapter_calendar_events[calendar events] for |
83 | configuring the schedule. | |
236bec37 | 84 | |
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85 | Error Handling |
86 | -------------- | |
236bec37 | 87 | |
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88 | If a replication job encounters problems, it is placed in an error state. |
89 | In this state, the configured replication intervals get suspended | |
90 | temporarily. The failed replication is repeatedly tried again in a | |
91 | 30 minute interval. | |
92 | Once this succeeds, the original schedule gets activated again. | |
236bec37 | 93 | |
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94 | Possible issues |
95 | ~~~~~~~~~~~~~~~ | |
236bec37 | 96 | |
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97 | Some of the most common issues are in the following list. Depending on your |
98 | setup there may be another cause. | |
236bec37 | 99 | |
728a3ea5 | 100 | * Network is not working. |
236bec37 | 101 | |
728a3ea5 | 102 | * No free space left on the replication target storage. |
236bec37 | 103 | |
c93fb4bf | 104 | * Storage with same storage ID available on the target node |
236bec37 | 105 | |
c93fb4bf | 106 | NOTE: You can always use the replication log to find out what is causing the problem. |
236bec37 | 107 | |
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108 | Migrating a guest in case of Error |
109 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
110 | // FIXME: move this to better fitting chapter (sysadmin ?) and only link to | |
111 | // it here | |
236bec37 | 112 | |
c93fb4bf | 113 | In the case of a grave error, a virtual guest may get stuck on a failed |
728a3ea5 | 114 | node. You then need to move it manually to a working node again. |
236bec37 | 115 | |
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116 | Example |
117 | ~~~~~~~ | |
236bec37 | 118 | |
c93fb4bf | 119 | Let's assume that you have two guests (VM 100 and CT 200) running on node A |
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120 | and replicate to node B. |
121 | Node A failed and can not get back online. Now you have to migrate the guest | |
122 | to Node B manually. | |
236bec37 | 123 | |
728a3ea5 | 124 | - connect to node B over ssh or open its shell via the WebUI |
236bec37 | 125 | |
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126 | - check if that the cluster is quorate |
127 | + | |
128 | ---- | |
129 | # pvecm status | |
130 | ---- | |
236bec37 | 131 | |
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132 | - If you have no quorum, we strongly advise to fix this first and make the |
133 | node operable again. Only if this is not possible at the moment, you may | |
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134 | use the following command to enforce quorum on the current node: |
135 | + | |
136 | ---- | |
137 | # pvecm expected 1 | |
138 | ---- | |
236bec37 | 139 | |
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140 | WARNING: Avoid changes which affect the cluster if `expected votes` are set |
141 | (for example adding/removing nodes, storages, virtual guests) at all costs. | |
5e8c8202 | 142 | Only use it to get vital guests up and running again or to resolve the quorum |
728a3ea5 | 143 | issue itself. |
236bec37 | 144 | |
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145 | - move both guest configuration files form the origin node A to node B: |
146 | + | |
147 | ---- | |
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148 | # mv /etc/pve/nodes/A/qemu-server/100.conf /etc/pve/nodes/B/qemu-server/100.conf |
149 | # mv /etc/pve/nodes/A/lxc/200.conf /etc/pve/nodes/B/lxc/200.conf | |
728a3ea5 | 150 | ---- |
236bec37 | 151 | |
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152 | - Now you can start the guests again: |
153 | + | |
154 | ---- | |
155 | # qm start 100 | |
156 | # pct start 200 | |
157 | ---- | |
236bec37 | 158 | |
728a3ea5 | 159 | Remember to replace the VMIDs and node names with your respective values. |
236bec37 | 160 | |
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161 | Managing Jobs |
162 | ------------- | |
236bec37 | 163 | |
1ff5e4e8 | 164 | [thumbnail="screenshot/gui-qemu-add-replication-job.png"] |
2a3d436c | 165 | |
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166 | You can use the web GUI to create, modify, and remove replication jobs |
167 | easily. Additionally, the command line interface (CLI) tool `pvesr` can be | |
728a3ea5 | 168 | used to do this. |
236bec37 | 169 | |
728a3ea5 | 170 | You can find the replication panel on all levels (datacenter, node, virtual |
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171 | guest) in the web GUI. They differ in which jobs get shown: |
172 | all, node- or guest-specific jobs. | |
236bec37 | 173 | |
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174 | When adding a new job, you need to specify the guest if not already selected |
175 | as well as the target node. The replication | |
728a3ea5 | 176 | xref:pvesr_schedule_time_format[schedule] can be set if the default of `all |
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177 | 15 minutes` is not desired. You may impose a rate-limit on a replication |
178 | job. The rate limit can help to keep the load on the storage acceptable. | |
236bec37 | 179 | |
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180 | A replication job is identified by a cluster-wide unique ID. This ID is |
181 | composed of the VMID in addition to a job number. | |
728a3ea5 | 182 | This ID must only be specified manually if the CLI tool is used. |
236bec37 | 183 | |
236bec37 | 184 | |
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185 | Command Line Interface Examples |
186 | ------------------------------- | |
236bec37 | 187 | |
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188 | Create a replication job which runs every 5 minutes with a limited bandwidth |
189 | of 10 Mbps (megabytes per second) for the guest with ID 100. | |
236bec37 | 190 | |
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191 | ---- |
192 | # pvesr create-local-job 100-0 pve1 --schedule "*/5" --rate 10 | |
193 | ---- | |
236bec37 | 194 | |
c93fb4bf | 195 | Disable an active job with ID `100-0`. |
236bec37 | 196 | |
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197 | ---- |
198 | # pvesr disable 100-0 | |
199 | ---- | |
236bec37 | 200 | |
c93fb4bf | 201 | Enable a deactivated job with ID `100-0`. |
236bec37 | 202 | |
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203 | ---- |
204 | # pvesr enable 100-0 | |
205 | ---- | |
236bec37 | 206 | |
c93fb4bf | 207 | Change the schedule interval of the job with ID `100-0` to once per hour. |
236bec37 | 208 | |
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209 | ---- |
210 | # pvesr update 100-0 --schedule '*/00' | |
211 | ---- | |
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212 | |
213 | ifdef::manvolnum[] | |
214 | include::pve-copyright.adoc[] | |
215 | endif::manvolnum[] |