 Hello everybody! Watch this video to see how to replace a faulty hard disk in a RAID system on Synology NAS DSM, and explore how to add more hard disks and migrate from RAID 5 to RAID 6. There is hardly a more terrifying sound than the one you hear when your hard disk breaks down or your NAS storage system detects a storage error. At that moment, you are so close to losing gigabytes of photos, videos and documents as your disk RAID appears to be in a degraded state. Now, integrity of your data largely depends on replacing a faulty disk properly and recovering the RAID system. If you use a NAS device to store your data, you'll be able to repair your RAID array easily, provided that you follow the correct approach. Before you replace the faulty disk, you need to identify the RAID type and understand if it supports replacement of disks without data loss. And find out how many hard disks can be down without interrupting the operation of this array. In today's video, I'll be using Synology devices and RAID 5 system for illustration. If your system uses RAID 5 technology to store data across an array of hard disks and only one disk is down, things are not so bad. This particular technology lets your NAS work as usual even if one hard disk is damaged, so you don't need to harrow and replace it with whatever disk you have at hand. However, your array has just lost its fault tolerance feature, since the RAID is going to crash as soon as one more disk breaks down. With as more, the remaining disks within the array are now experiencing more workload, because they have to do the work that used to be done by that faulty disk, so it's only a matter of time before other disks start suffering from errors. If one more hard disk breaks down, repairing the RAID and recovering data will become even more complicated and sometimes next to impossible. That is why it is recommended to replace the faulty disk as soon as possible. When a hard disk is out of order, NAS gives out a loud beep as a signal. Also, when you open DiskStation Manager, you will see a warning that one of the pools has a degraded status, and then it's recommended to replace the failing disk. If you set up notifications earlier, you will also receive an email notification about the error. For status, you need to identify a faulty hard disk. To do it, open the menu – Storage Manager, HDD. In a disk list, you can use the disk numbers to understand which disk needs to be replaced. Next to each disk you will see its status green or red depending on the disk condition. If everything works properly, there is a green word normal next to every disk. On the contrary, there will be a red word crashed or failed next to a faulty disk. In my case, the faulty hard disk is not displayed at all because it's completely out of order. Whether you ever start any manipulations concerning the hard disks, we strongly recommend backing up important data – marking all hard disks, writing down the order, and so on. After that, take the faulty disk out of its tray. Each tray is numbered. If there are no numbers, you can easily determine disk numbers by their position in the NAS device, counting from left to right. That is, if disk 5 is identified as faulty, it must be the fifth disk if you count from the left. When you find the faulty disk, take it out of the case. Synology NAS devices support hotswap feature. It means that you don't need to power off the device every time you want to replace a hard disk. Put a new disk into the tray instead of the faulty disk, or add a new disk to a vacant tray if there is one. Before adding a disk to the array, you should check it by running a smart test, open Storage Management, and go to HDD SSD tab. Open the new disk and click on the Health Info button. And then hit Smart Test on the right. Choose a test type and click Start. While the test is running, you'll be able to watch its status and progress. If the test is successful, you can add the disk to your array. Open the NAS Manager menu, Storage Manager, Storage Pool. Click on the Action button and select Repair from the list. In the window that opens, add the new disk to the list on the right and click Next. There will be a warning that all information on the disk is going to be erased. Click OK to confirm this action and then Apply. It starts the recovery process. When it's over, the Storage Pool status changes to normal. As you can see, all files stored on this device still remain intact. Hello, friends! If you need to recover deleted data, view or restore removed browser history. My software products will help you. Follow the link in the description. Download the necessary program for free, install it and analyze the disk. The utility will show you the data you can recover, so you will be able to view it or get it back. In our channel and blog, you will find solutions to any problem, from installing an operating system or configuring it to fixing possible bugs and errors or optimizing mobile gadgets. Our specialists will answer any questions you ask in your comments, under the videos or articles. As long as we have described the process of adding a hard disk, let's also explore how to add more hard disks to a Nest storage device and migrate the whole system from one rate e-level to another without losing data, for example, from rate 5 to rate 6. With Nest devices, you can change rate types for storage pools without worrying about possible data loss. For example, you can create a rate 1 storage pool, then change it to rate 5 as soon as more hard disks are added, and then transform it into rate 6 at a later time. To be able to change rate types, the Nest should have a sufficient number of hard disks installed in it. The minimal disk number for rate 5 is 3, and you need to add at least one more disk if you want to convert it into rate 6. Before changing the rate type, make sure that your storage pool is healthy. When adding disks to the array, their capacity should be more than the capacity of this most disk in this pool or equal to that capacity. Also, all the disks should be of one type. To change the rate level, open the menu, Storage Manager, Storage Pool. Click on the Action button and select Change Rate Type from the list. Choose rate 6. Next, add the disks to expand the disk array and click Next. When the pop-up window appears to warn you that all data on the disks will be erased, click OK. Check the configuration and click Apply to confirm it. It starts the process of adding new disks and rebuilding the array system. When it's over, you will see a notice saying that the rate has been changed successfully. With this kind of transformation, all the data stored on the disk array will remain unchanged, except for situations when the disk array can be damaged by a sudden power outage. When the disk array is being rebuilt, it involves recalculation of parity and overwriting data to the disks. If there is a power outage at that precise moment, this process is interrupted and all data stored in the volatile memory may be damaged, which results in a rate crash. In this case, access to all files will be lost and you'll need a specialized utility to restore data from the rate. On the screen, you can see that what may happen to a disk array if there is a power outage during the rebuilding process. As you see, the array crashed, the volume is not available and all the data is lost. Hopefully, this didn't happen to your system. To expand the volume, open the Volume tab, click on the Action button and select Configure from the list. Set the volume size here and click OK to confirm your choice. Now the volume has been expanded and the migration from Rate 5 to Rate 6 is successful. As you can see, all the files stored on the Rate 5 array have remained unchanged even after the array was rebuilt. But if there is a power outage during the rebuilding process and your rate system has crashed or you deleted important data by mistake, just use a reliable data recovery tool – Hetman Rate Recovery. It will automatically rebuild the damaged rate system and you'll be able to retrieve your files. This program supports all popular rate types and most NAS devices by various manufacturers. You can learn more about recovering data from Rate on Cynology NAS in another video. I'll put the link in the description. And that is all for now. Hopefully, this video was useful. Remember to click the Like button and subscribe to our channel. Leave comments to ask questions. Thank you for watching. Good luck.