Hard drives: Difference between revisions
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This article discusses the monitoring of hard drives, the best way to deal with hard drive failures, and general hard drive information. It explains how to make a complete backup of your Gentoo system into another hard drive. | This article discusses the monitoring of hard drives, the best way to deal with hard drive failures, and general hard drive information. It explains how to make a complete backup of your Gentoo system into another hard drive. | ||
= Partitions = | |||
* With the old (BIOS) partition table format, it is impossible to create a partition of more than 2TB. In order to create such a partition, you need to activate EFI GUID partition support in the kernel. Then you need to use GNU parted (and not fdisk) to create the partition: | |||
parted /dev/sdb | |||
mklabel gpt | |||
mkpart primary ext4 0 -1 | |||
= Filesystems = | = Filesystems = | ||
| Line 17: | Line 25: | ||
= Backing up your data and system = | = Backing up your data and system = | ||
= Making a stage4 = | == Making a stage4 == | ||
Under Linux everything is a file so it is easy to create a complete backup of your system. With Gentoo the best way is to generate a personal "stage4" file. Follow [http://gentoo-wiki.com/HOWTO_Custom_Stage4 this guide] on the Gentoo Wiki to do just that. | Under Linux everything is a file so it is easy to create a complete backup of your system. With Gentoo the best way is to generate a personal "stage4" file. Follow [http://gentoo-wiki.com/HOWTO_Custom_Stage4 this guide] on the Gentoo Wiki to do just that. | ||
| Line 25: | Line 33: | ||
* Be very careful about the /dev/null and /dev/console nodes. They are indeed needed to boot currently, even with udev. So it is mandatory to create these nodes statically, in the "real" /dev of the new hard drive. If you just follow the guide's instructions, you'll create the nodes after /dev points to something, so they won't reside on the real /dev directory of the hard drive. I advise to create them before chrooting and binding the /dev of the LiveCD. | * Be very careful about the /dev/null and /dev/console nodes. They are indeed needed to boot currently, even with udev. So it is mandatory to create these nodes statically, in the "real" /dev of the new hard drive. If you just follow the guide's instructions, you'll create the nodes after /dev points to something, so they won't reside on the real /dev directory of the hard drive. I advise to create them before chrooting and binding the /dev of the LiveCD. | ||
= Just copying everything = | == Just copying everything == | ||
* Copying everything using cp -ar will result in a working system. Just exclude dev, proc, sys directories. Even with a recent udev, you still need to create the /dev/null and/dev/console nodes in /dev. This is because they are needed *before* udev is started. | * Copying everything using cp -ar will result in a working system. Just exclude dev, proc, sys directories. Even with a recent udev, you still need to create the /dev/null and/dev/console nodes in /dev. This is because they are needed *before* udev is started. | ||
Revision as of 19:36, 15 April 2012
This article discusses the monitoring of hard drives, the best way to deal with hard drive failures, and general hard drive information. It explains how to make a complete backup of your Gentoo system into another hard drive.
Partitions
- With the old (BIOS) partition table format, it is impossible to create a partition of more than 2TB. In order to create such a partition, you need to activate EFI GUID partition support in the kernel. Then you need to use GNU parted (and not fdisk) to create the partition:
parted /dev/sdb mklabel gpt mkpart primary ext4 0 -1
Filesystems
- ext4 by default reserves a certain number of blocks for the super-user (5% by default). You can override that setting with tune2fs /dev/sdd1 -m 1 for example (it would set the number of blocks to 1%). You can see the current parameters by running:
tune2fs -l /dev/sdd1
- To reboot and check the filesystem (force a fsck), issue:
shutdown -Fr
- Never check (fsck) a mounted filesystem.
Monitoring your hard drives using SMART
Modern hard drives come with a self monitoring system called SMART. This system will apparently report problems and can detect in advance about 2/3 of hard drive failures. Under Linux, a set of tools, smartmontools, may be used to diagnose your hard drives. You can use the program smartctl manually, or install a daemon that will always run on your system and report failures.
Backing up your data and system
Making a stage4
Under Linux everything is a file so it is easy to create a complete backup of your system. With Gentoo the best way is to generate a personal "stage4" file. Follow this guide on the Gentoo Wiki to do just that.
- Warning: don't exclude "/usr/src/*" from the stage 4 as stated by the guide! /usr/src contains the kernel source, used by several packages, and more importantly, it also contains the kernel's .config file. If you exclude /usr/src in your stage4, you'll have to reedit your kernel configuration.
- Be very careful about the /dev/null and /dev/console nodes. They are indeed needed to boot currently, even with udev. So it is mandatory to create these nodes statically, in the "real" /dev of the new hard drive. If you just follow the guide's instructions, you'll create the nodes after /dev points to something, so they won't reside on the real /dev directory of the hard drive. I advise to create them before chrooting and binding the /dev of the LiveCD.
Just copying everything
- Copying everything using cp -ar will result in a working system. Just exclude dev, proc, sys directories. Even with a recent udev, you still need to create the /dev/null and/dev/console nodes in /dev. This is because they are needed *before* udev is started.