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Questions tagged [software-raid]

RAID solution handled by the operating system.

Software RAID is implemented in the OS. It uses CPU to handle the RAID setup. It is cheaper than hardware raid. It often doesn't support features which you can find with hardware raid like:

  • hot spare
  • fast rebuilding of an array
  • hot swapping
  • high write throughput

Another problem is that it uses the CPU and memory of the computer to perform all the tasks (hardware raidcards have a special cpu and memory for this task). Therefor generating more load on your system.

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How to add hot spare to software RAID1?

I have a CentOS 7 server. It is running a software RAID 1 mirroring three disks. I want to add a 4th disk to act as a hot spare. My intention is that in the event of a failure of one of the three disks being mirrored that the hot spare would…
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Poor write performance of software RAID10 array of 8 SSD drives

I have server with Supermicro X10DRW-i motherboard and RAID10 array of 8 KINGSTON SKC400S SSDs; OS is CentOS 6 # cat /proc/mdstat Personalities : [raid10] [raid1] md2 : active raid10 sdj3[9](S) sde3[4] sdi3[8] sdd3[3] sdg3[6] sdf3[5] sdh3[7]…
Evgeny Terekhov
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Disabling ext4 write barriers when using an external journal

I'm currently experimenting with different ways of improving write speeds to a fairly large, rotating disk-based, software-raid (mdadm) array on Debian using fast NVMe devices. I found that using a pair of such devices (raid1, mirrored) to store the…
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If a RAID controller fails, does it disrupt service until it's replaced?

If I have 2 drives in a RAID 1, and the Raid Controller fails, does that mean the websites on the server will have downtime until the controller is replaced? Or does everything still carry on as software raid automatically until the faulty raid card…
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How is LSI FastPath different from Software RAID?

This question pertains to SSDs on RAID levels without parity (like RAID 0, 1, 10). The recommended settings for FastPath are to set the Write Policy to Write Through, Read Policy to No Read Ahead and IO Policy to Direct. This disables the cache on…
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Linux Software RAID10: Mysterious renaming /dev/md0 to /dev/md127: Why?

During the last two nights we had mysterious events on a server running Ubuntu Linux 12.04 LTS with a Linux mdadm software RAID10: DeviceDisappeared /dev/md0 NewArray /dev/md127 Both messages appeared in the same second, on the same time as the…
pefu
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Setting up a bootable multi-device (RAID 1) using Linux Software RAID

I'm trying to setup a bootable software RAID that will contain the root filesystem and boot up Linux Mint Qiana. It will be used to run a few graphical monitoring applications in a small datacenter, as well as a simple terminal to access other LAN…
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Sizing of journal disks with Microsoft Storage Spaces parity volume

I'm currently speccing out a new backup server. It's going to be running Windows Server 2012 R2 with Direct Attached Storage, and I'm considering using Storage Spaces rather than using a RAID card. (As a ZFS fan, I can definitely see the advantages…
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SW SSD Raid 1 over HW RAID 10

A provider(data center) recommended I go with 1TB SSDs in a software RAID 1 over HW RAID 10 with mechanical drives. Their quote: Typically SSDs are most reliable than RAID cards and since you have less parts, there are less points of failure.…
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Linux software raid fails to include one device for one RAID1 array

One of my four Linux software raid arrays drops one of its two devices when I reboot my system. The other three arrays work fine. I am running RAID1 on kernel version 2.6.32-5-amd64. Every time I reboot, /dev/md2 comes up with only one device. I can…
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High I/O latency with software RAID, LUKS encrypted and LVM partitioned KVM setup

I found out a performance problems with a Mumble server, which I described in a previous question are caused by an I/O latency problem of unknown origin. As I have no idea what is causing this and how to further debug it, I'm asking for your ideas…
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How to create a software raid5 array without a spare

I am trying to create a software raid5 array using mdadm: $ linux # mdadm --create --verbose /dev/md0 --level=5 --raid-devices=4 --spare-devices=0 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 mdadm: layout defaults to left-symmetric mdadm: chunk size…
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What effect does RAID stripe size have on read-ahead settings?

I'm trying to figure out the correct read-ahead values to set on a RAID10 array, and I'm wondering if the RAID stripe size should factor into my considerations. I've heard conflicting information about this in the past. I once heard that you should…
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Is it necessary to have RAID in a virtual machine?

I have a Windows 2008 Enterprise on RAID 10 running Active Directory, Hosted Exchange, and a web server on HyperV VMs. Do I need a virtual RAID for Exchange? If so, why? Edit: thanks everyone for the answer. Very helpful!
Iternity
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What is the meaning of the 'Personalities' feature under /proc/mdstat

On some systems I see this : Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty] md1 : active raid1 sdb1[1] sda1[0] 10485696 blocks [2/2] [UU] md2 : active raid1 sdb2[1] sda2[0] 477371328…
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