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1 | [[chapter_pvesr]] | |
2 | ifdef::manvolnum[] | |
3 | pvesr(1) | |
4 | ======== | |
5 | :pve-toplevel: | |
6 | ||
7 | NAME | |
8 | ---- | |
9 | ||
10 | pvesr - Proxmox VE Storage Replication | |
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 | ||
27 | The `pvesr` command line tool manages the {PVE} storage replication | |
28 | framework. Storage replication brings redundancy for guests using | |
29 | local storage and reduces migration time. | |
30 | ||
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 | |
34 | an initial full sync. In the case of a node failure, your guest data is | |
35 | still available on the replicated node. | |
36 | ||
37 | The replication will be done automatically in configurable intervals. | |
38 | The minimum replication interval is one minute and the maximal interval is | |
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: | |
42 | ||
43 | Every guest can be replicated to multiple target nodes, but a guest cannot | |
44 | get replicated twice to the same target node. | |
45 | ||
46 | Each replications bandwidth can be limited, to avoid overloading a storage | |
47 | or server. | |
48 | ||
49 | Virtual guest with active replication cannot currently use online migration. | |
50 | Offline migration is supported in general. If you migrate to a node where | |
51 | the guests data is already replicated only the changes since the last | |
52 | synchronisation (so called `delta`) must be sent, this reduces the required | |
53 | time significantly. In this case the replication direction will also switch | |
54 | nodes automatically after the migration finished. | |
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 | |
61 | data must send over. After the migration the replication job continues to | |
62 | replicate this guest to the configured nodes. | |
63 | ||
64 | [IMPORTANT] | |
65 | ==== | |
66 | High-Availability is allowed in combination with storage replication, but it | |
67 | has the following implications: | |
68 | ||
69 | * redistributing services after a more preferred node comes online will lead | |
70 | to errors. | |
71 | ||
72 | * recovery works, but there may be some data loss between the last synced | |
73 | time and the time a node failed. | |
74 | ==== | |
75 | ||
76 | Supported Storage Types | |
77 | ----------------------- | |
78 | ||
79 | .Storage Types | |
80 | [width="100%",options="header"] | |
81 | |============================================ | |
82 | |Description |PVE type |Snapshots|Stable | |
83 | |ZFS (local) |zfspool |yes |yes | |
84 | |============================================ | |
85 | ||
86 | [[pvesr_schedule_time_format]] | |
87 | Schedule Format | |
88 | --------------- | |
89 | ||
90 | {pve} has a very flexible replication scheduler. It is based on the systemd | |
91 | time calendar event format.footnote:[see `man 7 systemd.time` for more information] | |
92 | Calendar events may be used to refer to one or more points in time in a | |
93 | single expression. | |
94 | ||
95 | Such a calendar event uses the following format: | |
96 | ||
97 | ---- | |
98 | [day(s)] [[start-time(s)][/repetition-time(s)]] | |
99 | ---- | |
100 | ||
101 | This allows you to configure a set of days on which the job should run. | |
102 | You can also set one or more start times, it tells the replication scheduler | |
103 | the moments in time when a job should start. | |
104 | With this information we could create a job which runs every workday at 10 | |
105 | PM: `'mon,tue,wed,thu,fri 22'` which could be abbreviated to: `'mon..fri | |
106 | 22'`, most reasonable schedules can be written quite intuitive this way. | |
107 | ||
108 | NOTE: Hours are set in 24h format. | |
109 | ||
110 | To allow easier and shorter configuration one or more repetition times can | |
111 | be set. They indicate that on the start-time(s) itself and the start-time(s) | |
112 | plus all multiples of the repetition value replications will be done. If | |
113 | you want to start replication at 8 AM and repeat it every 15 minutes until | |
114 | 9 AM you would use: `'8:00/15'` | |
115 | ||
116 | Here you see also that if no hour separation (`:`) is used the value gets | |
117 | interpreted as minute. If such a separation is used the value on the left | |
118 | denotes the hour(s) and the value on the right denotes the minute(s). | |
119 | Further, you can use `*` to match all possible values. | |
120 | ||
121 | To get additional ideas look at | |
122 | xref:pvesr_schedule_format_examples[more Examples below]. | |
123 | ||
124 | Detailed Specification | |
125 | ~~~~~~~~~~~~~~~~~~~~~~ | |
126 | ||
127 | days:: Days are specified with an abbreviated English version: `sun, mon, | |
128 | tue, wed, thu, fri and sat`. You may use multiple days as a comma-separated | |
129 | list. A range of days can also be set by specifying the start and end day | |
130 | separated by ``..'', for example `mon..fri`. Those formats can be also | |
131 | mixed. If omitted `'*'` is assumed. | |
132 | ||
133 | time-format:: A time format consists of hours and minutes interval lists. | |
134 | Hours and minutes are separated by `':'`. Both, hour and minute, can be list | |
135 | and ranges of values, using the same format as days. | |
136 | First come hours then minutes, hours can be omitted if not needed, in this | |
137 | case `'*'` is assumed for the value of hours. | |
138 | The valid range for values is `0-23` for hours and `0-59` for minutes. | |
139 | ||
140 | [[pvesr_schedule_format_examples]] | |
141 | Examples: | |
142 | ~~~~~~~~~ | |
143 | ||
144 | .Schedule Examples | |
145 | [width="100%",options="header"] | |
146 | |============================================================================== | |
147 | |Schedule String |Alternative |Meaning | |
148 | |mon,tue,wed,thu,fri |mon..fri |Every working day at 0:00 | |
149 | |sat,sun |sat..sun |Only on weekends at 0:00 | |
150 | |mon,wed,fri |-- |Only on Monday, Wednesday and Friday at 0:00 | |
151 | |12:05 |12:05 |Every day at 12:05 PM | |
152 | |*/5 |0/5 |Every five minutes | |
153 | |mon..wed 30/10 |mon,tue,wed 30/10 |Monday, Tuesday, Wednesday 30, 40 and 50 minutes after every full hour | |
154 | |mon..fri 8..17,22:0/15 |-- |Every working day every 15 minutes between 8 AM and 6 PM and between 10 PM and 11 PM | |
155 | |fri 12..13:5/20 |fri 12,13:5/20 |Friday at 12:05, 12:25, 12:45, 13:05, 13:25 and 13:45 | |
156 | |12,14,16,18,20,22:5 |12/2:5 |Every day starting at 12:05 until 22:05, every 2 hours | |
157 | |* |*/1 |Every minute (minimum interval) | |
158 | |============================================================================== | |
159 | ||
160 | Error Handling | |
161 | -------------- | |
162 | ||
163 | If a replication job encounters problems it will be placed in error state. | |
164 | In this state the configured replication intervals get suspended | |
165 | temporarily. Then we retry the failed replication in a 30 minute interval, | |
166 | once this succeeds the original schedule gets activated again. | |
167 | ||
168 | Possible issues | |
169 | ~~~~~~~~~~~~~~~ | |
170 | ||
171 | This represents only the most common issues possible, depending on your | |
172 | setup there may be also another cause. | |
173 | ||
174 | * Network is not working. | |
175 | ||
176 | * No free space left on the replication target storage. | |
177 | ||
178 | * Storage with same storage ID available on target node | |
179 | ||
180 | NOTE: You can always use the replication log to get hints about a problems | |
181 | cause. | |
182 | ||
183 | Migrating a guest in case of Error | |
184 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
185 | // FIXME: move this to better fitting chapter (sysadmin ?) and only link to | |
186 | // it here | |
187 | ||
188 | In the case of a grave error a virtual guest may get stuck on a failed | |
189 | node. You then need to move it manually to a working node again. | |
190 | ||
191 | Example | |
192 | ~~~~~~~ | |
193 | ||
194 | Lets assume that you have two guests (VM 100 and CT 200) running on node A | |
195 | and replicate to node B. | |
196 | Node A failed and can not get back online. Now you have to migrate the guest | |
197 | to Node B manually. | |
198 | ||
199 | - connect to node B over ssh or open its shell via the WebUI | |
200 | ||
201 | - check if that the cluster is quorate | |
202 | + | |
203 | ---- | |
204 | # pvecm status | |
205 | ---- | |
206 | ||
207 | - If you have no quorum we strongly advise to fix this first and make the | |
208 | node operable again. Only if this is not possible at the moment you may | |
209 | use the following command to enforce quorum on the current node: | |
210 | + | |
211 | ---- | |
212 | # pvecm expected 1 | |
213 | ---- | |
214 | ||
215 | WARNING: If expected votes are set avoid changes which affect the cluster | |
216 | (for example adding/removing nodes, storages, virtual guests) at all costs. | |
217 | Only use it to get vital guests up and running again or to resolve to quorum | |
218 | issue itself. | |
219 | ||
220 | - move both guest configuration files form the origin node A to node B: | |
221 | + | |
222 | ---- | |
223 | # mv /etc/pve/nodes/A/qemu-server/100.conf /etc/pve/nodes/B/qemu-server/100.conf | |
224 | # mv /etc/pve/nodes/A/lxc/200.conf /etc/pve/nodes/B/lxc/200.conf | |
225 | ---- | |
226 | ||
227 | - Now you can start the guests again: | |
228 | + | |
229 | ---- | |
230 | # qm start 100 | |
231 | # pct start 200 | |
232 | ---- | |
233 | ||
234 | Remember to replace the VMIDs and node names with your respective values. | |
235 | ||
236 | Managing Jobs | |
237 | ------------- | |
238 | ||
239 | [thumbnail="gui-qemu-add-replication-job.png"] | |
240 | ||
241 | You can use the web GUI to create, modify and remove replication jobs | |
242 | easily. Additionally the command line interface (CLI) tool `pvesr` can be | |
243 | used to do this. | |
244 | ||
245 | You can find the replication panel on all levels (datacenter, node, virtual | |
246 | guest) in the web GUI. They differ in what jobs get shown: all, only node | |
247 | specific or only guest specific jobs. | |
248 | ||
249 | Once adding a new job you need to specify the virtual guest (if not already | |
250 | selected) and the target node. The replication | |
251 | xref:pvesr_schedule_time_format[schedule] can be set if the default of `all | |
252 | 15 minutes` is not desired. You may also impose rate limiting on a | |
253 | replication job, this can help to keep the storage load acceptable. | |
254 | ||
255 | A replication job is identified by an cluster-wide unique ID. This ID is | |
256 | composed of the VMID in addition to an job number. | |
257 | This ID must only be specified manually if the CLI tool is used. | |
258 | ||
259 | ||
260 | Command Line Interface Examples | |
261 | ------------------------------- | |
262 | ||
263 | Create a replication job which will run every 5 minutes with limited bandwidth of | |
264 | 10 mbps (megabytes per second) for the guest with guest ID 100. | |
265 | ||
266 | ---- | |
267 | # pvesr create-local-job 100-0 pve1 --schedule "*/5" --rate 10 | |
268 | ---- | |
269 | ||
270 | Disable an active job with ID `100-0` | |
271 | ||
272 | ---- | |
273 | # pvesr disable 100-0 | |
274 | ---- | |
275 | ||
276 | Enable a deactivated job with ID `100-0` | |
277 | ||
278 | ---- | |
279 | # pvesr enable 100-0 | |
280 | ---- | |
281 | ||
282 | Change the schedule interval of the job with ID `100-0` to once a hour | |
283 | ||
284 | ---- | |
285 | # pvesr update 100-0 --schedule '*/00' | |
286 | ---- | |
287 | ||
288 | ifdef::manvolnum[] | |
289 | include::pve-copyright.adoc[] | |
290 | endif::manvolnum[] |