[posts] new : lxd-server-settings-for-production

_posts/2023-07-27-btrfs-snapshots-and-restore.md

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+---
+layout : post
+title : "LXD Cluster"
+categories : [ubuntu, lxd]
+published : false
+---
+
+
+### Reference
+* [btrfs](https://help.ubuntu.com/community/btrfs)
+
+* [How To Create Snapshots And Restore Your Linux System Using Btrfs](https://www.unixmen.com/snapshots-and-restore-linux-system-using-btrfs/)
+
+* [How to manage apt-btrfs-snapshot snapshots on Ubuntu](https://moritzmolch.com/blog/2506.html)

_posts/2023-07-27-lxd-cluster.md

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+---
+layout : post
+title : "LXD Cluster"
+categories : [ubuntu, lxd]
+published : false
+---
+
+
+
+
+```
+Error: Get "http://unix.socket/1.0": dial unix /var/snap/lxd/common/lxd/unix.socket: connect: connection refused
+
+
+sudo apt install sqlite3
+
+
+sudo sqlite3 /var/snap/lxd/common/lxd/database/local.db
+
+sqlite> .tables
+certificates  config        patches       raft_nodes    schema
+
+
+sqlite> select * from schema
+   ...> ;
+1|42|1689933924
+2|43|1690431075
+
+
+sqlite> delete from schema where id =2;
+sqlite> select * from schema;
+1|42|1689933924
+
+
+sqlite> select * from raft_nodes;
+1|10.10.10.13:8443|0|server03
+2|10.10.10.11:8443|1|server01
+
+sqlite> delete from raft_nodes where id =2;
+sqlite> select * from raft_nodes;
+1|10.10.10.13:8443|0|server03
+
+
+$ sudo snap start lxd
+
+```
+
+### Error: Error creating database: schema version '40' is more recent than expected '39'
+
+
+
+### [Managing the LXD snap](https://discuss.linuxcontainers.org/t/managing-the-lxd-snap/8178)
+
+LXD clusters must all run the same LXD version. 
+
+https://discuss.linuxcontainers.org/t/snap-fix-channel/9725
+
+snap switch lxd --channel=latest/stable
+
+sudo snap refresh lxd
+
+
+sudo snap install lxd --channel=latest/stable
+
+snap refresh lxd --channel=latest/stable
+
+To manually trigger a refresh on a cluster member and ensure that all cluster members are refreshing using the same phasing cohort, and thus get the same version, use:
+
+
+sudo journalctl -u snap.lxd.daemon.service -f -n200
+
+Production server:
+
+* Use the latest/stable channel if you need the latest features and can specify a frequent refresh window.
+* Use a snap refresh --hold lxd if you want to avoid the automatic release upgrade and have time to do manage the refresh cycle manually to ensure you get updates.
+* Use an $LTS/stable channel if you don’t need any of the features that were added since the last LTS release but still want bug fixes and security updates.
+* Set a refresh window to match your system maintenance window.
+
+
+### Reference
+* [Unable to complete LXD cluster node rename](https://discuss.linuxcontainers.org/t/unable-to-complete-lxd-cluster-node-rename/14723)
+
+* [Can't lxc list, no unix.socket connection refused](https://github.com/canonical/lxd/issues/5423)
+
+* [[SOLVED] LXD 3.18 Stopped working: unix.socket: connect: connection refused](https://discuss.linuxcontainers.org/t/solved-lxd-3-18-stopped-working-unix-socket-connect-connection-refused/6201)
+
+* [Wrong scheme version after upgrade](https://github.com/canonical/lxd/issues/3465)
+
+* [LXD Failed Cluster Upgrade - unable to update some nodes ](https://discuss.linuxcontainers.org/t/lxd-failed-cluster-upgrade-unable-to-update-some-nodes/7509)

_posts/2023-08-03-lxd-server-settings-for-production.md

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+---
+layout : post
+title : "Server settings for a LXD production setup"
+categories : [ubuntu, lxd]
+published : true
+---
+
+see a list of all your user’s limits on the system 
+```
+$ ulimit -a
+```
+
+
+### `/etc/security/limits.conf`
+add the following content:
+
+```
+#Each line describes a limit for a user in the form:
+#
+#<domain>        <type>  <item>  <value>
+#
+# Server settings for a LXD production setup
+#
+# Maximum number of open files
+*	soft	nofile	1048576	
+
+# Maximum number of open files
+*	hard	nofile	1048576	
+
+# Maximum number of open files
+root	soft	nofile	1048576	
+
+# Maximum number of open files
+root	hard	nofile	1048576	
+
+# Maximum locked-in-memory address space (KB)
+*	soft	memlock	unlimited	
+
+# Maximum locked-in-memory address space (KB)
+*	hard	memlock	unlimited	
+
+# Maximum locked-in-memory address space (KB), only need with bpf syscall supervision
+root	soft	memlock	unlimited	
+
+# Maximum locked-in-memory address space (KB), only need with bpf syscall supervision
+root	hard	memlock	unlimited	
+
+```
+
+* `*` denotes the rest of the system users
+* `soft` or `hard` is the limit type
+* `nofile` item is utilized for limiting
+
+
+### `/etc/sysctl.conf`
+add the following content:
+
+```
+#
+# Server settings for a LXD production setup
+#
+
+
+# Maximum number of concurrent asynchronous I/O operations 
+# (you might need to increase this limit further if you have 
+# a lot of workloads that use the AIO subsystem, for example, MySQL)
+# fs.aio-max-nr = 524288	# default recommend
+fs.aio-max-nr = 1048576
+
+# Upper limit on the number of events that can be queued to 
+# the corresponding inotify instance (see inotify)
+fs.inotify.max_queued_events = 1048576	
+
+# Upper limit on the number of inotify instances that 
+# can be created per real user ID (see inotify)
+fs.inotify.max_user_instances = 1048576	
+
+# Upper limit on the number of watches that can be 
+# created per real user ID (see inotify)
+fs.inotify.max_user_watches = 1048576	
+
+# Whether to deny container access to the messages in the kernel 
+# ring buffer (note that this will also deny access to non-root users on the host system)
+kernel.dmesg_restrict = 1	
+
+# Maximum size of the key ring that non-root users can use
+kernel.keys.maxbytes = 2000000	
+
+# Maximum number of keys that a non-root user can use 
+# (the value should be higher than the number of instances)
+kernel.keys.maxkeys = 2000	
+
+# Limit on the size of eBPF JIT allocations (on kernels < 5.15 
+# that are compiled with CONFIG_BPF_JIT_ALWAYS_ON=y, 
+# this value might limit the amount of instances that can be created)
+net.core.bpf_jit_limit = 1000000000	
+
+# Maximum number of entries in the IPv4 ARP table 
+# (increase this value if you plan to create over 1024 instances - 
+# otherwise, you will get the error neighbour: ndisc_cache: neighbor 
+# table overflow! when the ARP table gets full and the instances 
+# cannot get a network configuration; see ip-sysctl)
+net.ipv4.neigh.default.gc_thresh3 = 8192	
+
+# Maximum number of entries in IPv6 ARP table 
+# (increase this value if you plan to create over 1024 instances - 
+# otherwise, you will get the error neighbour: ndisc_cache: 
+# neighbor table overflow! when the ARP table gets full 
+# and the instances cannot get a network configuration; see ip-sysctl)
+net.ipv6.neigh.default.gc_thresh3 = 8192	
+
+# Maximum number of memory map areas a process may have 
+# (memory map areas are used as a side-effect of calling malloc, 
+# directly by mmap and mprotect, and also when loading shared libraries)
+vm.max_map_count = 262144	
+```
+
+
+To activate the new setting, run the following command:
+```shell
+$ sudo sysctl -p /etc/sysctl.conf
+```
+
+### Reference
+* [Server settings for a LXD production setup](https://documentation.ubuntu.com/lxd/en/latest/reference/server_settings/#server-settings)