What are odds MySQL table can be recovered?

This is the most asked question. Every single customer asks if their MySQL table can be recovered. Although it’s not possible to answer that with 100% confidence there are ways to estimate recovery chances. I will describe few tricks.

Generally speaking, if data is on media there are high odds TwinDB data recovery toolkit can fetch it. Where to look for depends on accident type.

Online MySQL data recovery toolkit

On our Data Recovery portal you can upload an .ibd file and check if the InnoDB tablespace contains any good records. The table space may be corrupt. The tool should handle that.

DROP TABLE or DATABASE with innodb_file_per_table=OFF

If …

There are at least two cases when it makes sense to take an image from a corrupted hard drive as soon as possible: disk hardware errors and corrupted filesystem. Faulty hard drives can give just one chance to read a block, so there is no time for experiments. The similar picture with corrupted filesystems. Obviously something went wrong, it’s hard to predict how the operating system will behave next second and whether it will cause even more damage.

Save disk image to local storage

Probably the best and fastest way is to plug the faulty disk into a healthy server and save the disk image locally:

# dd if=/dev/sdb of=/path/on/sda/faulty_disk.img  conv=noerror

Where /dev/sdb is the faulty disk and faulty_disk.img is the image on the healthy /dev/sda disk.

conv=noerrror tells dd to continue reading even if …