diff --git a/docs/books/admin_guide/09-backups.md b/docs/books/admin_guide/09-backups.md index ecdc7ff97..ef5c421cb 100644 --- a/docs/books/admin_guide/09-backups.md +++ b/docs/books/admin_guide/09-backups.md @@ -25,9 +25,9 @@ In this chapter you will learn how to back up and restore your data with Linux. !!! Note - Throughout this chapter the command structures use "device" to specify both a target location for backup, and the source location when restoring. The device can be either external media or a local file. You should get a feel for this as the chapter unfolds, but you can always refer back to this note for clarification if you need to. + Throughout this chapter, the command structures use "device" to specify both a target location for backup and the source location when restoring. The device can be either external media or a local file. You should get a feel for this as the chapter unfolds, but you can always refer back to this note for clarification if you need to. -The backup will answer a need to conserve and restore data in a sure and effective way. +The backup will answer the need to conserve and restore data effectively. The backup allows you to protect yourself from the following: @@ -35,7 +35,7 @@ The backup allows you to protect yourself from the following: * **Deletion**: voluntary or involuntary. Human or technical. Virus, ... * **Integrity**: data becomes unusable. -No system is infallible, no human is infallible, so to avoid losing data, it must be backed up to be able to restore after a problem. +No system is infallible, and no human is infallible, so to avoid losing data, it must be backed up so that it can be restored after a problem. The backup media should be kept in another room (or building) than the server so that a disaster does not destroy the server and the backups. @@ -43,16 +43,16 @@ In addition, the administrator must regularly check that the media are still rea ## Generalities -There are two principles, the **backup** and the **archive**. +There are two principles: the **backup** and the **archive**. * The archive destroys the information source after the operation. * The backup preserves the source of information after the operation. -These operations consist of saving information in a file, on a peripheral or a supported media (tapes, disks, ...). +These operations consist of saving information in a file, on a peripheral, or on a supported media (tapes, disks, etc.). ### The process -Backups require a lot of discipline and rigor from the system administrator. System administrator need to consider the following issues before performing backup operations: +Backups require a lot of discipline and rigor from the system administrator. System administrators need to consider the following issues before performing backup operations: * What is the appropriate medium? * What should be backed up? @@ -84,20 +84,20 @@ In addition to these issues, system administrators should also consider factors !!! Tip - Before a system change, it can be useful to make a backup. However, there is no point in backing up data every day that is only changed every month. + Before a system change, it can be useful to make a backup. However, there is no point in backing up data every day that only changes every month. ### Restoration methods -Depending on the utilities available, it will be possible to perform several types of restorations. +Depending on the utilities available, performing several types of restorations will be possible. * **Complete restoration**: trees, ... * **Selective restoration**: part of tree, files, ... -It is possible to restore a whole backup, but it is also possible to restore only a part of it. However, when restoring a directory, the files created after the backup are not deleted. +It is possible to restore a whole backup or only a part of it. However, when restoring a directory, the files created after the backup are not deleted. !!! Tip - To recover a directory as it was at the time of the backup, it is necessary to completely delete its contents before launching the restoration. + To recover a directory as it was before the backup, it is necessary to completely delete its contents before launching the restoration. ### The tools and related technologies @@ -129,7 +129,7 @@ The commands we will use here are `tar` and `cpio`. ### Naming convention -The use of a naming convention makes it possible to quickly target the contents of a backup file and thus avoid hazardous restorations. +The use of a naming convention allows one to quickly target the contents of a backup file and thus avoid hazardous restorations. * name of the directory; * utility used; @@ -138,11 +138,11 @@ The use of a naming convention makes it possible to quickly target the contents !!! Tip - The name of the backup must be an explicit name. + The name of the backup must be explicit. !!! Note - The notion of extension under Linux does not exist. In other words, our use of extensions here is for the human operator. If the systems administrator sees a `.tar.gz` or `.tgz` file extension, for instance, then he knows how to deal with the file. + The notion of extension under Linux does not exist. In other words, we use extensions here for the human operator. If the systems administrator sees a `.tar.gz` or `.tgz` file extension, for instance, then he knows how to deal with the file. ### Contents of a backup @@ -184,7 +184,7 @@ The right questions to ask are: !!! Warning - Before a restoration, it is important to take time to think about and determine the most appropriate method to avoid mistakes. + Before a restoration, it is important to consider and determine the most appropriate method to avoid mistakes. Restorations are usually performed after a problem has occurred that needs to be resolved quickly. A poor restoration can, in some cases, make the situation worse. @@ -192,7 +192,7 @@ Restorations are usually performed after a problem has occurred that needs to be The default utility for creating backups on UNIX systems is the `tar` command. These backups can be compressed by `bzip2`, `xz`, `lzip`, `lzma`, `lzop`, `gzip`, `compress` or `zstd`. -`tar` allows you to extract a single file or a directory from a backup, view its contents or validate its integrity. +`tar` allows you to extract a single file or a directory from a backup, view its contents, or validate its integrity. #### Estimate the size of a backup @@ -213,7 +213,7 @@ $ tar cjf - /directory/to/backup/ | wc -c #### Naming convention for a `tar` backup -Here is an example of a naming convention for a `tar` backup, knowing that the date is to be added to the name. +Here is an example of a naming convention for a `tar` backup, knowing that the date will be added to the name. | keys | Files | Suffix | Functionality | |---------|---------|------------------|----------------------------------------------| @@ -249,7 +249,7 @@ Example: !!! Tip - The hyphen (`-`) in front of the `tar` keys is not necessary! + The hyphen (`-`) in front of the `tar` keys is unnecessary! ##### Create a backup in absolute mode @@ -287,7 +287,7 @@ tar cvzf backup.tar.gz dirname/ !!! Note - The `.tgz` extension is an equivalent extension to `.tar.gz`. + The `.tgz` extension is equivalent to `.tar.gz`. !!! Note @@ -311,9 +311,9 @@ tar cvfj backup.tar.bz2 dirname/ ##### Compression `compress`, `gzip`, `bzip2`, `lzip` and `xz` -Compression, and consequently decompression, will have an impact on resource consumption (time and CPU usage). +Compression, and consequently decompression, will impact resource consumption (time and CPU usage). -Here is a ranking of the compression of a set of text files, from least to most efficient: +Here is a ranking of the compression of a set of text files from least to most efficient: * compress (`.tar.Z`) * gzip (`.tar.gz`)