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Questions tagged [raid]

RAID, an acronym originally for Redundant Array of Inexpensive Disks (today usually interpreted as referred to as Redundant Array of Independent Disks), is a technology that provides increased storage performance and reliability through redundancy by spreading data across multiple disks using various algorithms (RAID-levels). RAID can be implemented in hardware storage controllers, or in software, usually as operating system/kernel features.

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What are the different widely used RAID levels and when should I consider them?

This is a Canonical Question about RAID levels. What are: the RAID levels typically used (including the RAID-Z family)? deployments are they commonly found in? benefits and pitfalls of each?
MDMarra
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Why is RAID not a backup?

When someone mentions RAID in a conversation about backups, invariably someone declares that "RAID is not a backup." Sure, for striping, that's true. But what's the difference between redundancy and a backup?
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Is it better practice to buy RAID disks individually vs. in bulk?

This may sound like an odd question, but it's generated some spirited discussion with some of my colleagues. Consider a moderately sized RAID array consisting of something like eight or twelve disks. When buying the initial batch of disks, or buying…
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Is it possible to reboot a Linux OS without rebooting the hardware?

Is there a way to reboot a Linux system (Debian in particular) without rebooting the hardware? I have a RAID controller that takes a bit to get itself running before the OS starts up, and I would like it if there was a way to quickly reboot the…
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Software vs hardware RAID performance and cache usage

I've been reading a lot on RAID controllers/setups and one thing that comes up a lot is how hardware controllers without cache offer the same performance as software RAID. Is this really the case? I always thought that hardware RAID cards would…
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RAID - software vs. hardware

I have always used hardware based RAID because it (IMHO) is on the right level (feel free to dispute this), and because OS failures are more common to me than hardware issues. Thus if the OS fails the RAID is gone and so is the data, whereas - on a…
Robert MacLean
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What is the current state (2016) of SSDs in RAID?

There are plenty of resources available online that discuss using SSD drives in RAID configurations - however these mostly date back a few years, and the SSD ecosystem is very fast-moving - right as we're expecting Intel's "Optane" product release…
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What is better LVM on RAID or RAID on LVM?

I currently have LVM on software RAID, but I'd like to ask you what you think it is better solution, maybe some pros and cons? Edit: It is about software raid on lvm or lvm on software raid. I know than hardware raid is better if we are thinking…
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How to interrupt software raid resync?

I want to interrupt a running resync operation on a debian squeeze software raid. (This is the regular scheduled compare resync. The raid array is still clean in such a case. Do not confuse this with a rebuild after a disk failed and was…
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Is bit rot on hard drives a real problem? What can be done about it?

A friend is talking with me about the problem of bit rot - bits on drives randomly flipping, corrupting data. Incredibly rare, but with enough time it could be a problem, and it's impossible to detect. The drive wouldn't consider it to be a bad…
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What risks are there with mixing SSD models in RAID?

Aside from one type of disk bottlenecking the other, are there any other problems with mixing SSD models in RAID? My problem is, I need to upgrade the storage in a server with 4x Samsung 845DC EVO 960GB in RAID10. These drives are not available…
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File Server - Storage configuration: RAID vs LVM vs ZFS something else...?

We are a small company that does video editing, among other things, and need a place to keep backup copies of large media files and make it easy to share them. I've got a box set up with Ubuntu Server and 4 x 500 GB drives. They're currently set up…
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Should I RAID my SSDs?

I have a couple of SATA hard disks RAIDed for safety in my machine, because I'm worried about the drive having some sort of mechanical failure and losing my data. I'm considering switching to an SSD next year when the prices have come done a bit. Is…
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How beneficial are self-healing filesystems for general usage?

I have recently looked into advanced filesystems (Btrfs, ZFS) for data redundancy and availability and got interested in the additional functionality they provide, especially their "self-healing" capabilities against data corruption. However, I…
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How to view status of software RAID 1 resynching?

I have two 500 GB disks and yesterday I mirrored first drive to the second one using software RAID 1. PC has now been on for 30 hours. Both disks say "Resynching", but there is no progress indicator. In addition, there is a small yellow exclamation…
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