Discourse升级因25G droplet磁盘空间不足而失败

安装
2 
root@DO-Discourse:/var/discourse# df -h
文件系统      大小  已用  可用  已用%  挂载点
udev            448M     0  448M    0%  /dev
tmpfs            99M  1.1M   98M    2%  /run
/dev/vda1        25G   18G  6.2G   75%  /
tmpfs           491M     0  491M    0%  /dev/shm
tmpfs           5.0M     0  5.0M    0%  /run/lock
tmpfs           491M     0  491M    0%  /sys/fs/cgroup
/dev/vda15      105M  9.2M   96M    9%  /boot/efi
overlay          25G   18G  6.2G   75%  /var/lib/docker/overlay2/d319d95263d87c2a75a4bc9a9f03a25ea7f6eb1f7bac687e7ae7d45522939dc0/merged
/dev/loop10      56M   56M     0  100%  /snap/core18/2284
/dev/loop7       44M   44M     0  100%  /snap/snapd/14978
/dev/loop5       62M   62M     0  100%  /snap/core20/1361
/dev/loop2       68M   68M     0  100%  /snap/lxd/22526
/dev/loop1       62M   62M     0  100%  /snap/core20/1376
/dev/loop3       44M   44M     0  100%  /snap/snapd/15177
/dev/loop4       56M   56M     0  100%  /snap/core18/2344
/dev/loop6       68M   68M     0  100%  /snap/lxd/22753
tmpfs            99M     0   99M    0%  /run/user/0
root@DO-Discourse:/var/discourse#