Ytdyklly

Edit: a follow-up question: Recover a mongo database deleted by rm.

My developer committed a huge mistake and we cannot find our Mongo database anywhere in the server.

He logged into the server, and saved the following shell under ~/crontab/mongod_back.sh:

#!/bin/sh

DUMP=mongodump

OUT_DIR=/data/backup/mongod/tmp  // 备份文件临时目录

TAR_DIR=/data/backup/mongod      // 备份文件正式目录

DATE=`date +%Y_%m_%d_%H_%M_%S`   // 备份文件将以备份对间保存

DB_USER=Guitang                  // 数库操作员

DB_PASS=qq■■■■■■■■■■■■■■■■■■■■■  // 数掘库操作员密码

DAYS=14                          // 保留最新14天的份

TARBAK="mongod_bak_$DATE.tar.gz" // 备份文件命名格式

cd $OUT_DIR                      // 创建文件夹

rm -rf $OUT_DIR/*                // 清空临时目录

mkdir -p $OUT_DIR/$DATE          // 创建本次备份文件夹

$DUMP -d wecard -u $DB_USER -p $DB_PASS -o $OUT_DIR/$DATE  // 执行备份命令

tar -zcvf $TAR_DIR/$TAR_BAK $OUT_DIR/$DATE       // 将份文件打包放入正式

find $TAR_DIR/ -mtime +$DAYS -delete             // 除14天前的旧备

And then he ran it and it outputted permission denied messages, so he pressed Ctrl+C. The server shut down automatically. He tried to restart it but got a grub error:

He contacted AliCloud, the engineer connected the disk to another working server so that he could check the disk. Looks like some folders are gone, including /data/ where the mongodb is!

1. We don't understand how the script could destroy the disk including /data/;


2. And of course, is it possible to get the /data/ back?

PS: He did not take snapshot of the disk before.

PS2: As people mention "backups" a lot, we have lots of important users and data coming these 2 days, the purpose of this action was to backup them (for the first time), then they turned out to be entirely deleted.

Easy enough. The // sequence isn't a comment in bash (# is).

The statement OUT_DIR=x // text had no effect*.

Thus what was finally executed was rm -rf /*. The directories that the user couldn't remove gave permission errors, but some directories placed directly underneath / apparently could be removed. You need to restore from backup.

* The peculiar form of bash statement A=b c d e f is roughly similar to:

export A=b

c d e f

unset A

Hence script suceeded to do this:

export OUT_DIR=/data/mongo/tmp

// some text   # gives error as `//` isn't an executable file!

unset OUT_DIR

1) He erroneously assumed that // was a bash comment. It is not, only # is.

The shell interpreted // text as a normal command, and did not find a binary called //, and did nothing.

In bash, when you have a variable assignment (OUT_DIR=/data/backup/mongod/tmp) directly preceding a command (// text), it only sets the variable while running the command. Therefore, it unsets OUT_DIR immediately, and when the rm line is reached, OUT_DIR is now unset, and rm -rf / is now called, deleting everything you have permission to delete.

2) The solution is the same as all rm -rf / cases: restore from backup. There is no other solution because you do not have physical access to the hard drive.

1) Bash comments start with #. Sorry for your loss.
2) Restore from backup is the only way to proceed here, unfortunately.