RAID Creation
From Linux Raid Wiki
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MD devices are created using the <code>Create</code> mode of <code>mdadm</code>. | MD devices are created using the <code>Create</code> mode of <code>mdadm</code>. | ||
| − | + | As of lvm2 2.02.87 and linux 2.6.32, LVM can be used to create MD-RAID volumes (<tt>lvcreate --type=raidN --stripes=numstripes</tt>). This offers a strong guarantee that the component devices won't be exposed. | |
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| + | With mdadm, you specify the raid device to create, the raid mode (raid0, raid1, raid10, raid5, raid6 etc) and the component devices. | ||
You can also configure many aspects of your array: | You can also configure many aspects of your array: | ||
| − | * [[RAID superblock formats|superblock format]] | + | * [[RAID superblock formats|superblock format]]: <tt>--metadata=1.1</tt> or <tt>--metadata=1.2</tt> is recommended. 0.90 and 1.0 are at the end of the device and risk exposing desynced contents if the superblock is damaged |
* [[device name]] | * [[device name]] | ||
* [[label|name or label]] | * [[label|name or label]] | ||
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<blockquote>“Why does linux raid do 'resync' when I create a clean array? Can I skip that?”</blockquote> | <blockquote>“Why does linux raid do 'resync' when I create a clean array? Can I skip that?”</blockquote> | ||
The answer is usually "NO". For more details see [[Initial Array Creation]] | The answer is usually "NO". For more details see [[Initial Array Creation]] | ||
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Revision as of 15:54, 19 September 2013
MD devices are created using the Create mode of mdadm.
As of lvm2 2.02.87 and linux 2.6.32, LVM can be used to create MD-RAID volumes (lvcreate --type=raidN --stripes=numstripes). This offers a strong guarantee that the component devices won't be exposed.
With mdadm, you specify the raid device to create, the raid mode (raid0, raid1, raid10, raid5, raid6 etc) and the component devices.
You can also configure many aspects of your array:
- superblock format: --metadata=1.1 or --metadata=1.2 is recommended. 0.90 and 1.0 are at the end of the device and risk exposing desynced contents if the superblock is damaged
- device name
- name or label
- RAID-level
- superblock
- chunk size
- rounding
- layout
- Write-intent bitmap
- write-mostly
- partitionable
One question that frequently comes up with linux raid is:
“Why does linux raid do 'resync' when I create a clean array? Can I skip that?”
The answer is usually "NO". For more details see Initial Array Creation
