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In this video, we'll talk about options to repair file systems. Actually, you need to

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understand what is going on. And that is because many problems are fixed automatically when

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you boot because file system journal on XFS or the transaction log on XFS. This journal

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and transaction log mean that file systems basically are auto healing. So when you are

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booting and an error was encountered, the file system will do a rollback of the previous

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situation and you'll be all set. EXT file systems can be checked manually as well using

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the FS check utility, which is the utility that you can also use to repair. And on some

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more cases, you might need to have to do that. On XFS, it's even more rare with the XFS repair

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utility is available. If you are going to use these utilities, you need to make sure

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that you are in emergency mode because normally these utilities require the file system not to

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be opened at all. So let me show you how you can start these utilities. Starting here.

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So to start it, I need to reboot and get access to the group boot prompt. Getting access to the

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group boot prompt is always a little bit of a guess. You need to press escape at the right

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moment. And as you can see, I just succeeded. So here we see the default kernel that my system

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wants to start. I'm pressing E for edit. And then I'm looking up the line that starts with Linux

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and ends with R-H-Z-B and quiet, which is default on CentOS. I'm giving it the option init is

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slash bin slash bash. Init is bin bash is the most minimal troubleshooting mode. And the nice

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thing about this minimal troubleshooting mode is that your file systems are not yet

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mounted in a rewritable way. And also, you are not required to enter a root password. You just

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get access to a root shell. Now there, I'm going to use LSBLK, where I can see my block devices,

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and none of these block devices is mounted. So I need to use the appropriate utility.

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And in order to do so, I am going to use slash user slash sbin, where all of my XFS

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utilities are. And there we can see there is the XFS repair utility. So let's do that on dev sda1,

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which should be by my boot device. And oh boy, there I can see that XFS repair is failing.

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Bad primary superblock. And why is it giving me bad primary superblock? Well, that is because I

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made a mistake. And we did it on a VFAT file system. In order to use XFS repair and other

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repair utilities, they are file system specific. So you need to be on the right file system.