RAID6 is a method of configuring fault-tolerant hard drive storage. It is similar to RAID5, but differs in that it writes two sets of parity information, thus can survive the simultaneous failure of two hard drives.

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Raid 6 with HP P421?

I cant figure out if I need to buy a licens key to enable Raid 6 for this raid controller? I can't find where to buy one and I find pages where it says that its now free. sudo hpssacli ctrl slot=1 ...
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1answer
77 views

Can RAID 6 support 3 or more parities? [closed]

It doesn't seem right to me that people are using RAID 1+0, RAID 5+0, or RAID 6+0 instead of using a RAID with 3 or more parities (akin to RAID 6) because the latter has a better reliability given the ...
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6answers
3k views

Why is RAID 1+6 not a more common layout?

Why are the nested RAID levels 1+5 or 1+6 almost unheard of? The nested RAID levels Wikipedia article is currently missing their sections. I don't understand why they are not more common than RAID ...
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1answer
46 views

Hardware Raid6 - Which FS and mountoptions + basic questions

I've got a new system (Ubuntu 14.04 on an SSD), including 2*Megaraid 9271-8i controller+cachecade & BBU connected to the backplanes of the case. Each controller has 8 WD RED 3TB (4096 Physical ...
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1answer
69 views

Repairing RAID6 with two drive issues mdadm

I have had two disk failures on my RAID6 array. I have added two new disks and did the following: I ran mdadm /dev/md1 --remove on the two disks I set up my RAID on the 1st partition of each disk ...
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1answer
65 views

How to migrate RAID-6 from 5 disks to 4 disks while increasing disk sizes

I am having a quite complex problem and while I found solutions to individual steps (and already applied some of them in different contexts), I am not quite sure on how to do the whole procedure ...
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1answer
52 views

Linux soft RAID6 how to identify last failing drive [duplicate]

I have a RAID6 array that had been neglected, and just had the third drive fail. I want to do a ddrescue of the last drive to fail to try to recover the RAID, however I don't know how to identify ...
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1answer
194 views

Backup Solutions for 20 TB of data [duplicate]

First, some background on out situation. We're a small-medium business who has around 20 TB of data on two different NAS's, and that number grows by at least 10% annually. 90% of this data we need to ...
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1answer
153 views

mdadm RAID6 to RAID60

Is it easy to convert a RAID6 to a RAID60? Right now, I have an 8-drive RAID6. I'm looking to upgrade to a 3U 16-bay system and thinking of having a 16-drive RAID60. Is it possible to move my ...
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1answer
50 views

Running RAID 6 with a smaller drive

It looks like one of my hard drives failed in our RAID 6 (4 x 2TB) configuration. Unfortunately, I only have immediate access to a 1TB drive. Would there be an issue with temporarily replacing the 2TB ...
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11answers
11k views

How bad is it really to install Linux on one big partition?

We will be running CentOS 7 on our new server. We have 6 x 300GB drives in raid6 internal to the server. (Storage is largely external in the form of a 40TB raid box.) The internal volume comes to ...
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1answer
64 views

RAID6 generates quite a IO wait at relatively low TPS

I have a RAID6 array made of 9 SATA3 disks @7200 RPM, 4TB in size. I have them partitioned with Gparted Live as GPT partitions, starting at the first megabyte. I am concerned about the read speed. ...
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1answer
70 views

First 500MB of RAID6 array is wiped, how to recover?

We have a RAID6 array with 12 disks on a 3ware 9650SE-12ML controller. An engineer of our server provider issued this command by mistake: sudo dd if=/dev/zero of=/dev/sde bs=1M count=500; sync; ...
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1answer
508 views

recovering a corrupt degraded btrfs RAID6, need to manually clear an inode

I have a btrfs RAID 6. I have lousy hard drives, one failed, and another failed during recovery. Now I am without parity and cannot rebuild--a third drive is throwing read errors on a few sectors. ...
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2answers
91 views

soft raid6 recover second disk fault

I had a disk failure in a hosted system and had the failed drive replaced. During recovery, a disk error on a different drive occurred. when the original error occurred: md2 : active raid6 ...
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1answer
135 views

S/W RAID6 and 4k sector format — slow resync

I'm looking for reason why Linux software RAID-6 re-sync is much slower than I expected. I have used 6 WDC WD40EFRX HDDs (with 4k physical sectors) to create RAID-6 array. $ sudo mdadm -v -C ...
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1answer
124 views

System wont boot from degraded RAID6

I have a Debian Wheezy with 3 Partitions as RAID6. MD0 is for Root and OS, MD1 is for SWAP and MD2 for Files. While copy files to MD2 the system reports kernel panic and halts. I have had shutdown on ...
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0answers
124 views

RAID6 Ubuntu rebuild - how to calculate best parameters for fastest rebuild

I am doing a resync on a RAID6 array and I am looking at some 2 days to complete. I looked here for hints on how to speed it up, but I have, instead, managed to slow it down! HW details are: 10x 4TB ...
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1answer
170 views

Expanding RAID6 with LVM

My question is a bit broader than the question title, but here is my situation: I have Synology Hybrid Raid (SHR) built on 2 x 2TB drives. I want to migrate to a software-RAID on a homegrown linux ...
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0answers
156 views

Need help recovering RAID 6 array

My CentOS 6.5 server had its primary drive fail the other day. Our hosting company replaced the primary drive and reinstalled the OS. The system is up and running, but the 15TB of RAID6 storage isn't ...
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3answers
383 views

mdadm raid6 built, but no mounting or fsck

I had some problems with my RAID 6 drive on mdadm recently. No LVM in between. Two drives died, and were pulled out while the machine was powered down. Now, I boot up the system, and cannot mount the ...
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2answers
1k views

ZFS: 3 devices: what's the difference between mirror and raidz2?

It would seem like with 3 devices, it's possible to configure a ZFS pool with either mirror or raidz2 mode. What's the difference in performance and reliability? (In regards to reliability, I'm ...
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2answers
587 views

Strange performance issue with Dell R7610 and LSI 2208 RAID controller

Connecting controller to any of the three PCIe x16 slots yield choppy read performance around 750 MB/sec Lowly PCIe x4 slot yields steady 1.2 GB/sec read Given same files, same Windows Server 2008 ...
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1answer
1k views

How is the parity calculation in a RAID 6? [duplicate]

In a RAID5, the parity block is a XOR calculation of the rest of blocks but, in a RAID6, the second block parity is the XOR calculation of what blocks? ...
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0answers
31 views

Which Inode Size for Files bigger than 60mb

I will create a new server and wondered about the I-node options default, news, large file and largefile4. I searched the net and found explanations about 256kb until 4mb for one I-node, but i cant ...
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1answer
286 views

Which partition size for fresh install Debian Wheezy with 6 Disk in Raid?

i want to install Wheezy on a System with 6x3TB Disk. The aim is to use the most of it for a samba share. My idea is to make: 1 partition on each disk for gpt with 100MB 1 partition for "/" with 3GB ...
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1answer
263 views

Concerns of simultaneous failure of SSD Raid1

Since SSD's have a write limit requiring wear leveling one would assume that all things being equal 2 identical SSD drives would wear nearly identically if they mirror data writes. When one drive ...
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1answer
188 views

mdadm raid6 array reports incorrect size in df -h after grow

I've recently grown a 5x 3tb mdadm raid6 array (8tb) with a sixth disc in fedora 18, and after full rebuild and check, "mdadm --detail /dev/md127" returns the below: Version : 1.2 Creation ...
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4answers
363 views

Hardware Acceleration for MD RAID?

Is it possible, or feasible, or even sensible to consider hardware acceleration for MD RAID? I am referring more here to RAID6 type levels where there is a computation overhead. My thinking is that ...
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2answers
94 views

Progressive upgrade of a RAID array

I have a 16 disk backup RAID6 array. Currently, those 16 disks have the following specs; 500 GB 16 and 64MB cache 3 Gb/s SATA I would like to begin upgrading these disks if possible, primarily ...
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1answer
64 views

Safest approach when designing storage server [duplicate]

We are planing cloud solution for our customers and we are really concerned with designing safest storage servers for their files. This storage won't be IO demanding, as it will contain only files ...
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2answers
169 views

Disabling Server 2003 Wonderware App Server Page File on VMware

There are so many threads on whether you should mess with the page file or not. This scenario describes a unique circumstance that is real world in my production enviornment. The conclusion I've ...
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1answer
418 views

Linux mdadm --grow RAID6: Something wrong - reshape aborted

I have a RAID60 that I want to expand. The current is: 2 axles each having 9 disks + 2 spares. The future is: 4 axles each having 10 disks + 1 spare. So I need to do some --grow to reshape the ...
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0answers
111 views

Online expansion PERC700 RAID6 server

I have a Dell PowerEdge r510, with 5 HDDs in a RAID6 configuration. I'd like to add a 6th disk (and, in the future, more) to grow the hardware RAID configuration. I have a logical volume, in which ...
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1answer
948 views

3ware raid controller, unit unusable, several degraded disks

I was switching the disk drives in my server, running RAID 6 on 5 disks on a 3ware 9650SE controller, for newer disks and have run into a problem. The two first disks went fine, I took out one disk ...
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1answer
540 views

RAID-5 or RAID-6 - is RAID-5 really that bad? [duplicate]

Possible Duplicate: Which is better: RAID5 + 1 Hotspare / RAID6? I need to decide myself between RAID5 and RAID6. The servers have a hardware-RAID controller and 6 drives each. The ...
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2answers
658 views

Linux software RAID6: rebuild slow

I am trying to find the bottleneck in the rebuilding of a software raid6. ## Pause rebuilding when measuring raw I/O performance # echo 1 > /proc/sys/dev/raid/speed_limit_min # echo 1 > ...
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1answer
276 views

Abort raid6 expansion on Adaptec 52445 SATA RAID?

I am expanding my raid6 array from 18x2Tb to 20x2Tb disks and after 3 weeks status shows: Logical device Task: Logical device : 0 Task ID : 105 Current ...
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1answer
581 views

Using 2-port LSI 9286-8e card to control 24 SAS HDDs

I would like to rely on a RAID-on-chip solution to control 24 SAS hard drives in a direct-attached environment. How would you approach this to get best bandwidth given that I'd like to spend less ...
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1answer
960 views

Linux software RAID6: 3 drives offline - how to force online?

This is similar to 3 drives fell out of Raid6 mdadm - rebuilding? except that it is not due to a failing cable. Instead the 3rd drive fell offline during rebuild of another drive. The drive failed ...
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1answer
428 views

mdadm: superblock on /dev/sdd1 doesn't match others - assembly aborted

OS: Debian Squeeze Kernel: 2.6.32-5-amd64 mdadm version: 3.1.4 (31 August 2010) mdarrays md1 = raid1 (this is working) (devices: /dev/sd[fg]1) md0 = raid6 (previously raid5, ...
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7answers
772 views

Which RAID/LVM configuration for new 2x8TB file server is safest?

I just built a totally new PC to be a fileserver. It has one 60gb SSD for OS (ubuntu 12.04), and 8 2tb data drives in it. I am looking for the safest, most stable way to set up a single giant ...
4
votes
1answer
391 views

3 drives fell out of Raid6 mdadm - rebuilding?

i had an mdadm raid6 array with 13x1TB drives. Within 10 minutes 3 of these drives fell out of the array... we assume bad cable to the controller card and replaced, however now we need to get the ...
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2answers
2k views

High IO latency on ESXi 4.1 on HP DL580 G7

at my Company we were experiencing some weird spikes on IO latency on one of our ESXi instances. we've spend 24h figuring out whats wrong and no clue so far. after giving up we put all the disks ...
4
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1answer
4k views

3Ware 9650SE RAID-6, two degraded drives, one ECC, rebuild stuck

This morning I came in the office to discover that two of the drives on a RAID-6, 3ware 9650SE controller were marked as degraded and it was rebuilding the array. After getting to about 4%, it got ...
6
votes
2answers
6k views

Convert a Smart Array RAID5 array to a RAID6 (ADG) variant

I have an HP MicroServer (N36L) with a SmartArray P410 controller, a 512MB BBWC unit and four (4) 2TB disks connected. Three of those disks are configured as a single RAID5 array and one is left ...
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2answers
2k views

Linux mdadm software RAID 6 - does it support bit corruption recovery?

Wikipedia says "RAID 2 is the only standard RAID level, other than some implementations of RAID 6, which can automatically recover accurate data from single-bit corruption in data." Does anyone know ...
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1answer
501 views

3ware 9650SE-24M8 INOPERABLE data recovery

I have a raid6 array with 16 hdds. Two harddrives had failed (device error), but when I went to replace them, I pulled out one wrong disk! Now the raid array is INOPERABLE. Is there any way to ...
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5answers
2k views

Which disk is bad in raid6 array

Server: Ubuntu Lucid RAID controller: Adaptec 3805 8 disks in RAID6 on HP Proliant DL180 G5 Hardware My kern.log tells me that I have an error on sdb, as shown below: [2740390.344436] sd 4:0:1:0: ...
9
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2answers
1k views

Areca 1280ml RAID6 volume set failed

Today we hit some kind of worst case scenario and are open to any kind of good ideas. Here is our problem: We are using several dedicated storage servers to host our virtual machines. Before I ...