webmin备份错误No space left on device的现象如下，导致备份中断：

Creating TAR file of home directory ..
.. TAR failed! cat: write error: No space left on device

gzip: stdout: Broken pipe
/bin/tar: -: Wrote only 4096 of 10240 bytes
/bin/tar: Error is not recoverable: exiting now

这是因为/tmp目录空间太小导致的。我们可以df -h 查看/tmp大小，如果小于您单个网站的大小，那么就会出现上面错误

[root@www.654z.com]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb8              45G  5.7G   37G  14% /
/dev/sdb7              67G  3.6G   60G   6% /var
/dev/sdb6              90G  1.2G   84G   2% /usr
/dev/sdb5             245G  6.0G  227G   3% /home
/dev/sdb3             2.0G   36M  1.9G   2% /tmp
/dev/sdb1             190M   17M  164M  10% /boot

webmin/virtualmin备份错误No space left on device的解决办法

To solve your current issue though, I'd go into Webmin -> Webmin -> Webmin Configuration -> Advanced, and change what the "Temporary files directory" is set to... perhaps something like /var/tmp, but anything other than /tmp would work.

webmin-advanced-options.png

change-default-tmp-dir.png