{"id":470,"date":"2015-02-18T13:44:23","date_gmt":"2015-02-18T19:44:23","guid":{"rendered":"https:\/\/www.ppsstudios.com\/blog\/?p=470"},"modified":"2018-08-07T11:09:00","modified_gmt":"2018-08-07T17:09:00","slug":"linux-find-what-is-preventing-you-from","status":"publish","type":"post","link":"https:\/\/www.ppsstudios.com\/blog\/2015\/02\/linux-find-what-is-preventing-you-from\/","title":{"rendered":"Linux – Find what is Preventing You from Unmounting a Drive"},"content":{"rendered":"

Disclaimer: I’ve had this problem for probably four months, ever since I started running Plex Media Server on my headless linux machine at home, whilst storing all my actual media on a nice external portable drive. Usually I just yank it, but then I watch the drive letters run themselves up obscenely high before I need to reboot.<\/i><\/p>\n

So you’ve gone through the process of mounting your drive in Linux:<\/p>\n

> sudo fdisk -l\r\nDevice Boot = \/dev\/sdb1 (and a bunch of other technical information regarding drive size, id, and such)\r\n>\r\n> sudo mount -t ntfs-3g \/dev\/sdb1 \/media\/TOSHIBA\r\n><\/pre>\n
You run a bunch of stuff, get it all working, then find you need to take the drive to work the next day, so you try to unmount it.<\/p>\n
> sudo umount \/media\/TOSHIBA\r\numount: \/media\/TOSHIBA: device is busy.\r\n(In some cases useful info about processes that use the device is found by lsof(8) or fuser(1))\r\n>\r\n<\/pre>\n
<\/p>\n
Well, being a Windows guy at heart, and not really understanding why everything here needs to be so technical, this message never told me ANYTHING. I would try typing just plain “lsof” or “lsof(8)” or “fuser(1)” with no useful results.<\/p>\n
Then I asked a friend.<\/p>\n
“lsof\u00a0| grep <stuff><\/span>\u00a0,” he said.<\/p>\n
“Like,\u00a0<stuff><\/span>\u00a0 would be the \/dev\/sdb1<\/span>\u00a0?”<\/p>\n
“Yeah.”<\/p>\n
So I tried it:<\/p>\n
> sudo lsof | grep \/dev\/sdb1\r\nmount.ntf\u00a0\u00a0\u00a0\u00a0 2096\u00a0\u00a0\u00a0\u00a0\u00a0 root\u00a0\u00a0\u00a0\u00a0 3u\u00a0\u00a0\u00a0\u00a0 BLK\u00a0\u00a0\u00a0 8,33 0x1d1ba997e00\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2897182\u00a0\u00a0 \/dev\/sdb1<\/pre>\n
“Oh,” he said. “Try the mount path.\u00a0\/dev\/sdb1<\/span>\u00a0 is the device which is mounted somewhere else.”<\/p>\n
> sudo lsof | grep \/media\/TOSHIBA\r\n><\/pre>\n
“Nothing,” I said. “Just a blank line.”<\/p>\n
“Looks like no program has any file open on it?”<\/p>\n
“Let me try again.”<\/p>\n
bash\u00a0\u00a0\u00a0\u00a0 2068\u00a0\u00a0\u00a0\u00a0 daniel\u00a0\u00a0\u00a0 cwd\u00a0\u00a0\u00a0 DIR\u00a0\u00a0\u00a0 8,33\u00a0\u00a0\u00a0\u00a0 8192\u00a0\u00a0\u00a0 17459\u00a0 \/media\/TOSHIBA\r\ngrep \u00a0\u00a0\u00a0 2254\u00a0\u00a0\u00a0\u00a0 root \u00a0\u00a0 \u00a0\u00a0 cwd\u00a0\u00a0\u00a0 DIR\u00a0\u00a0\u00a0 8,33\u00a0\u00a0\u00a0\u00a0 8192\u00a0\u00a0\u00a0\u00a0 17459\u00a0 \/media\/TOSHIBA\r\nlsof \u00a0\u00a0\u00a0 2255\u00a0\u00a0\u00a0\u00a0 root\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 cwd\u00a0\u00a0\u00a0 DIR\u00a0\u00a0\u00a0 8,33\u00a0\u00a0\u00a0\u00a0 8192\u00a0\u00a0\u00a0\u00a0 17459\u00a0 \/media\/TOSHIBA<\/pre>\n
“Ahh…It may have been because I was still cd’d into it.”<\/p>\n
“Yes!”<\/p>\n
So lessons learned:<\/p>\n