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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 | Guests with replication enabled can currently only be migrated offline. |
50 | Only changes since the last replication (so-called `deltas`) need to be | |
51 | transferred if the guest is migrated to a node to which it already is | |
52 | replicated. This reduces the time needed significantly. The replication | |
53 | direction automatically switches if you migrate a guest to the replication | |
54 | target node. | |
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55 | |
56 | For example: VM100 is currently on `nodeA` and gets replicated to `nodeB`. | |
57 | You migrate it to `nodeB`, so now it gets automatically replicated back from | |
58 | `nodeB` to `nodeA`. | |
59 | ||
60 | If you migrate to a node where the guest is not replicated, the whole disk | |
c93fb4bf | 61 | data must send over. After the migration, the replication job continues to |
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62 | replicate this guest to the configured nodes. |
63 | ||
64 | [IMPORTANT] | |
65 | ==== | |
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66 | High-Availability is allowed in combination with storage replication, but there |
67 | may be some data loss between the last synced time and the time a node failed. | |
728a3ea5 | 68 | ==== |
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69 | |
70 | Supported Storage Types | |
71 | ----------------------- | |
72 | ||
73 | .Storage Types | |
74 | [width="100%",options="header"] | |
75 | |============================================ | |
76 | |Description |PVE type |Snapshots|Stable | |
77 | |ZFS (local) |zfspool |yes |yes | |
78 | |============================================ | |
79 | ||
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80 | [[pvesr_schedule_time_format]] |
81 | Schedule Format | |
82 | --------------- | |
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83 | Replication uses xref:chapter_calendar_events[calendar events] for |
84 | configuring the schedule. | |
236bec37 | 85 | |
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86 | Error Handling |
87 | -------------- | |
236bec37 | 88 | |
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89 | If a replication job encounters problems, it is placed in an error state. |
90 | In this state, the configured replication intervals get suspended | |
91 | temporarily. The failed replication is repeatedly tried again in a | |
92 | 30 minute interval. | |
93 | Once this succeeds, the original schedule gets activated again. | |
236bec37 | 94 | |
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95 | Possible issues |
96 | ~~~~~~~~~~~~~~~ | |
236bec37 | 97 | |
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98 | Some of the most common issues are in the following list. Depending on your |
99 | setup there may be another cause. | |
236bec37 | 100 | |
728a3ea5 | 101 | * Network is not working. |
236bec37 | 102 | |
728a3ea5 | 103 | * No free space left on the replication target storage. |
236bec37 | 104 | |
c93fb4bf | 105 | * Storage with same storage ID available on the target node |
236bec37 | 106 | |
c93fb4bf | 107 | NOTE: You can always use the replication log to find out what is causing the problem. |
236bec37 | 108 | |
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109 | Migrating a guest in case of Error |
110 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
111 | // FIXME: move this to better fitting chapter (sysadmin ?) and only link to | |
112 | // it here | |
236bec37 | 113 | |
c93fb4bf | 114 | In the case of a grave error, a virtual guest may get stuck on a failed |
728a3ea5 | 115 | node. You then need to move it manually to a working node again. |
236bec37 | 116 | |
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117 | Example |
118 | ~~~~~~~ | |
236bec37 | 119 | |
c93fb4bf | 120 | Let's assume that you have two guests (VM 100 and CT 200) running on node A |
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121 | and replicate to node B. |
122 | Node A failed and can not get back online. Now you have to migrate the guest | |
123 | to Node B manually. | |
236bec37 | 124 | |
728a3ea5 | 125 | - connect to node B over ssh or open its shell via the WebUI |
236bec37 | 126 | |
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127 | - check if that the cluster is quorate |
128 | + | |
129 | ---- | |
130 | # pvecm status | |
131 | ---- | |
236bec37 | 132 | |
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133 | - If you have no quorum, we strongly advise to fix this first and make the |
134 | node operable again. Only if this is not possible at the moment, you may | |
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135 | use the following command to enforce quorum on the current node: |
136 | + | |
137 | ---- | |
138 | # pvecm expected 1 | |
139 | ---- | |
236bec37 | 140 | |
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141 | WARNING: Avoid changes which affect the cluster if `expected votes` are set |
142 | (for example adding/removing nodes, storages, virtual guests) at all costs. | |
5e8c8202 | 143 | Only use it to get vital guests up and running again or to resolve the quorum |
728a3ea5 | 144 | issue itself. |
236bec37 | 145 | |
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146 | - move both guest configuration files form the origin node A to node B: |
147 | + | |
148 | ---- | |
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149 | # mv /etc/pve/nodes/A/qemu-server/100.conf /etc/pve/nodes/B/qemu-server/100.conf |
150 | # mv /etc/pve/nodes/A/lxc/200.conf /etc/pve/nodes/B/lxc/200.conf | |
728a3ea5 | 151 | ---- |
236bec37 | 152 | |
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153 | - Now you can start the guests again: |
154 | + | |
155 | ---- | |
156 | # qm start 100 | |
157 | # pct start 200 | |
158 | ---- | |
236bec37 | 159 | |
728a3ea5 | 160 | Remember to replace the VMIDs and node names with your respective values. |
236bec37 | 161 | |
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162 | Managing Jobs |
163 | ------------- | |
236bec37 | 164 | |
1ff5e4e8 | 165 | [thumbnail="screenshot/gui-qemu-add-replication-job.png"] |
2a3d436c | 166 | |
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167 | You can use the web GUI to create, modify, and remove replication jobs |
168 | easily. Additionally, the command line interface (CLI) tool `pvesr` can be | |
728a3ea5 | 169 | used to do this. |
236bec37 | 170 | |
728a3ea5 | 171 | You can find the replication panel on all levels (datacenter, node, virtual |
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172 | guest) in the web GUI. They differ in which jobs get shown: |
173 | all, node- or guest-specific jobs. | |
236bec37 | 174 | |
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175 | When adding a new job, you need to specify the guest if not already selected |
176 | as well as the target node. The replication | |
728a3ea5 | 177 | xref:pvesr_schedule_time_format[schedule] can be set if the default of `all |
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178 | 15 minutes` is not desired. You may impose a rate-limit on a replication |
179 | job. The rate limit can help to keep the load on the storage acceptable. | |
236bec37 | 180 | |
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181 | A replication job is identified by a cluster-wide unique ID. This ID is |
182 | composed of the VMID in addition to a job number. | |
728a3ea5 | 183 | This ID must only be specified manually if the CLI tool is used. |
236bec37 | 184 | |
236bec37 | 185 | |
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186 | Command Line Interface Examples |
187 | ------------------------------- | |
236bec37 | 188 | |
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189 | Create a replication job which runs every 5 minutes with a limited bandwidth |
190 | of 10 Mbps (megabytes per second) for the guest with ID 100. | |
236bec37 | 191 | |
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192 | ---- |
193 | # pvesr create-local-job 100-0 pve1 --schedule "*/5" --rate 10 | |
194 | ---- | |
236bec37 | 195 | |
c93fb4bf | 196 | Disable an active job with ID `100-0`. |
236bec37 | 197 | |
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198 | ---- |
199 | # pvesr disable 100-0 | |
200 | ---- | |
236bec37 | 201 | |
c93fb4bf | 202 | Enable a deactivated job with ID `100-0`. |
236bec37 | 203 | |
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204 | ---- |
205 | # pvesr enable 100-0 | |
206 | ---- | |
236bec37 | 207 | |
c93fb4bf | 208 | Change the schedule interval of the job with ID `100-0` to once per hour. |
236bec37 | 209 | |
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210 | ---- |
211 | # pvesr update 100-0 --schedule '*/00' | |
212 | ---- | |
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213 | |
214 | ifdef::manvolnum[] | |
215 | include::pve-copyright.adoc[] | |
216 | endif::manvolnum[] |