A serious issue has been detected in Seagate 7200.11 hard drives.
The sad news is for owners of Seagate 7200.11 hard drives, especially 500GB, 750GB and 1TB models with SD15 firmware: users report that after turning off and turning on these hard drives, they simply cease to be detected in the BIOS or are determined by the amount of "0GB" The Seagate forum is literally teeming with such stories. According to preliminary information, the problem is caused by the firmware. Perhaps in the near future, Seagate will release a firmware patch, but it will not be possible to use it on already locked hard drives. However, users of the Seagate forum write that the majority manage to recover their disks with the help of special equipment.
At the moment, the solution is to refuse to turn off the computer, plus the presence of an uninterruptible power supply unit is recommended.