[pbs-devel] [PATCH proxmox-backup v3] etc: provide and enable mount unit for /run/proxmox-backup

[pbs-devel] [PATCH proxmox-backup v3] etc: provide and enable mount unit for /run/proxmox-backup

[Christian Ebner]

Since the introduction of per-chunk file locks for datastores with s3
backend, the inodes on the tmpfs backing /run/proxmox-backup might be
to limited, the kernel dynamically calculating the limit based on
available system memory [0]. To not limit the number of inodes,
provide a systemd mount unit to create a dedicated tmpfs for
/run/proxmox-backup.

The mount unit is only enabled but not started by dh_installsystemd,
so this has only effect after a reboot.

[0] https://docs.kernel.org/filesystems/tmpfs.html

Fixes: https://forum.proxmox.com/threads/176228/
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
Reviewed-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
Changes since v2 (thanks @Fabian for review):
- use `backup` user and group instead of numerical id

 debian/proxmox-backup-server.install |  1 +
 "etc/run-proxmox\\x2dbackup.mount"   | 14 ++++++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 "etc/run-proxmox\\x2dbackup.mount"

diff --git a/debian/proxmox-backup-server.install b/debian/proxmox-backup-server.install
index d06f026cf..11dd037e8 100644
--- a/debian/proxmox-backup-server.install
+++ b/debian/proxmox-backup-server.install
@@ -6,6 +6,7 @@ etc/proxmox-backup-daily-update.timer /usr/lib/systemd/system/
 etc/proxmox-backup-proxy.service /usr/lib/systemd/system/
 etc/proxmox-backup.service /usr/lib/systemd/system/
 etc/removable-device-attach@.service /usr/lib/systemd/system/
+etc/run-proxmox\x2dbackup.mount /usr/lib/systemd/system/
 usr/bin/pmt
 usr/bin/pmtx
 usr/bin/proxmox-tape
diff --git "a/etc/run-proxmox\\x2dbackup.mount" "b/etc/run-proxmox\\x2dbackup.mount"
new file mode 100644
index 000000000..ea6c5569f
--- /dev/null
+++ "b/etc/run-proxmox\\x2dbackup.mount"
@@ -0,0 +1,14 @@
+[Unit]
+Description=Mount tmpfs at /run/proxmox-backup
+Conflicts=umount.target
+Before=local-fs.target umount.target
+
+[Mount]
+Type=tmpfs
+What=tmpfs
+Where=/run/proxmox-backup
+# Unlimited inodes as this stores per-chunk file locks
+Options=rw,nosuid,nodev,noexec,relatime,uid=backup,gid=backup,nr_inodes=0,mode=755,inode64
+
+[Install]
+WantedBy=local-fs.target
-- 
2.47.3



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[pbs-devel] applied: [PATCH proxmox-backup v3] etc: provide and enable mount unit for /run/proxmox-backup

[Thomas Lamprecht]

On Thu, 20 Nov 2025 11:05:23 +0100, Christian Ebner wrote:
> Since the introduction of per-chunk file locks for datastores with s3
> backend, the inodes on the tmpfs backing /run/proxmox-backup might be
> to limited, the kernel dynamically calculating the limit based on
> available system memory [0]. To not limit the number of inodes,
> provide a systemd mount unit to create a dedicated tmpfs for
> /run/proxmox-backup.
> 
> [...]

Applied, thanks!

[1/1] etc: provide and enable mount unit for /run/proxmox-backup
      commit: 37a9304882bd360667794b610ce9cfa6a0c91dc2


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