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.
Questions tagged [raid]
3585 questions
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How do I differentiate "fake RAID" from real RAID?
The Ubuntu wiki page on FakeRaid says the following:
[A] number of hardware products ...
claim to be IDE or SATA RAID
controllers... Virtually none of these
are true hardware RAID controllers.
Instead, they are simply multi-channel
disk…
cdleary
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Why is RAID 0 classed as RAID when it's not redundant?
I've worked in IT quite a number of years, so I know what a RAID array is, what RAID 0 is, RAID 1, 5, 6, 10, 50, 60, etc., but something sprung to mind in a recent conversation at work; if RAID stands for redundant array of independent (or…
Gavin Burke
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To improve SQL performance, why not just put lots of RAM rather than having faster hard disks?
People keep telling me that in order to improve an SQL server's performance, buy the fastest hard disks possible with RAID 5, etc.
So I was thinking, instead of spending all the money for RAID 5 and super-duper fast hard disks (which isn't cheap by…
user1034912
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Can we mount multiple disks as one directory?
Is there a way to mount the different disks as one directory?
Assuming I have some disks with ext4 partitions:
/dev/sda1 1Tb mounted as /store1
/dev/sda2 2Tb mounted as /store2
/dev/sdb1 2Tb mounted as /store3
/dev/sdb2 2Tb mounted as /store4
I…
Arman
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What are the performance differences between Raid 0,1,5,6,10
I have heard/read different performance stories on the various raid flavors. I am curious what the agreed upon best answer is.
James Moore
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Should I defrag my RAID volumes?
It seems to me that since RAID volumes are logical (as opposed to physical), the layout that the OS believes they have might not correspond to the actual phsyical layout.
So does defrag make sense for RAID?
Aidan Ryan
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Consumer (or prosumer) SSD's vs. fast HDD in a server environment
What are the pro's and con's of consumer SSDs vs. fast 10-15k spinning drives in a server environment? We cannot use enterprise SSDs in our case as they are prohibitively expensive. Here's some notes about our particular use case:
Hypervisor with…
David Budiac
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When using software RAID and LVM on Linux, which IO scheduler and readahead settings are honored?
In the case of multiple layers (physical drives -> md -> dm -> lvm), how do the schedulers, readahead settings, and other disk settings interact?
Imagine you have several disks (/dev/sda - /dev/sdd) all part of a software RAID device (/dev/md0)…
andrew311
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How to monitor the hard disk status behind Dell PERC H710 Raid Controller with CentOS 6?
I have a Dell server running CentOS 6 using PERC H710 Raid Controller card with Raid 5 setup and I want to monitor the hard disk failure/working status behind the Raid Controller.
Then I should be able to use a bash script to monitor the hard disk…
Xianlin
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Do I need to RAID Fusion-io cards?
Can I run reliably with a single Fusion-io card installed in a server, or do I need to deploy two cards in a software RAID setup?
Fusion-io isn't very clear (almost misleading) on the topic when reviewing their marketing materials Given the cost of…
ewwhite
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What is the difference between a HBA card and a RAID card?
I thought I knew the difference between HBA and RAID.
In my mind, HBA is offloading from the main motherboard/CPU and is simply JBOD... usually has an external SAS ports, whilst a RAID card does the same job as HBA but adds all the nice RAID levels…
William Hilsum
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If a RAID5 system experiences a URE during rebuild, is all the data lost?
I understand the argument regarding larger drives' increased likelihood of experiencing a URE during a rebuild, however I'm not sure what the actual implications are for this. This answer says that the entire rebuild fails, but does this mean that…
mboratko
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Is there a difference between RAID 10 (1+0) and RAID 01 (0+1)?
I've seen both of these listed, both being striped and mirrored across multiple drives, but is the a difference between them that I'm not picking up on?
notnot
25
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4 answers
Do raid controllers syncronize HDD platter rotation?
I'm in the market for a new storage solution. While researching various specs one of my coworkers said that some raid controllers can synchronize HDD rotation to the effect of all drives' sector/block 0 passes under the reading head at the same…
Mxx
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Scaling databases with cheap SSD hard drives
I hope that many of you are working with high traffic database-driven websites, and chances are that your main scalability issues are in the database. I noticed a couple of things lately:
Most large databases require a team of DBAs in order to…
Dennis Kashkin
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