RAID, an acronym for Redundant Array of Independent Disks (sometimes incorrectly referred to as Redundant Array of Inexpensive Disks), is a technology that provides increased storage functions and reliability through redundancy. -Wikipedia

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107
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2answers
15k views

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? ...
56
votes
13answers
25k views

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 ...
20
votes
5answers
15k views

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 ...
7
votes
1answer
6k views

How exactly does a SAS SFF-8087 breakout cable work? + RAID/connection questions

Please let me know if my question does not makes any sense as I am not sure if I am interpreting it correctly from my thoughts due to my lack of technical knowledge on this. If I am using a ...
2
votes
2answers
3k views

Non-volatile cache RAID controllers: what kind of protection is there against NVCACHE failure?

The battery back-up (BBU) model: admin enables write-back cache with BBU writes are cached to the RAID controller's RAM (major performance benefit) the battery saves uncommitted and cached data in ...
16
votes
5answers
11k views

Possible to get SSD TRIM (discard) working on ext4 + LVM + software RAID in Linux?

We use RAID1+0 with md on Linux (currently 2.6.37) to create an md device, then use LVM to provide volume management on top of the device, and then use ext4 as our filesystem on the LVM volume groups. ...
3
votes
3answers
2k views

What is the memory module on a RAID card needed for?

As above, what is the reason for needing a memory module on a RAID card? The card I am looking at (HP P410) comes with either 256MB or 512MB but unsure which to get and why.
42
votes
10answers
6k views

RAID - software vs. hardware

I have always used hardware based raid because it (IMHO) it's on the right level (feel free to dispute this) and that OS failures are more common to me than hardware issues. Thus if the OS fails the ...
5
votes
3answers
6k views

mkfs Operation Takes Very Long on Linux Software Raid 5

I've set-up a Linux software raid level 5 consisting of 4 * 2 TB disks. The disk array was created with a 64k stripe size and no other configuration parameters. After the initial rebuild I tried to ...
4
votes
3answers
5k views

explain md's raid10,f2

I know how most of the various RAID's work. But I stumbled on the recommended raid10,f2 mode while researching linux software raid. I don't really understand how it works on 2 or 3 disks. could ...
3
votes
4answers
15k views

Disabling RAID feature on HP Smart Array P400

I'm planning to use ZFS on my system (HP ML370 G5, Smart Array P400, 8 SAS disk). I want ZFS to manage all disks individually, so it can utilize better scheduling (i.e. I want to use software RAID ...
1
vote
1answer
634 views

How to create a bootable redundant Debian system with a 3 or 4 (or more) disk software raid10?

How do I create a Debian system which is bootable, has a software raid10 and will still boot when I take out one or more (bootable) disks? I would like to use as few disks as possible, preferably 3 or ...
22
votes
13answers
2k views

High Failure Rate of Large Drives?

I recently deployed a server with 5x 1TB drives (I won't mention their brand, but it was one of the big two). I was initially warned against getting large capacity drives, as a friend advised me that ...
10
votes
2answers
794 views

What counts as a 'large' raid 5 array?

A recent issue with a Buffalo TeraStation NAS here in my office has got me investigating Raid 5. I've found a few different articles talking about the unsuitability of using raid 5 in large arrays, ...
7
votes
3answers
32k views

How to find RAID configuration/level and RPM speed having only remote access to the server?

Having only remote access (no physical access), to a server (that is SSH), how do I (or may be is it possible): find out whether it is RAID configured or not? If it is RAID configured, whether it ...
10
votes
5answers
9k views

How do you monitor the health of a mirrored disk in Windows?

I have a Mirrored Dynamic disk on my Windows 2003 Server. How do you monitor the health of the volume? Is there a way to have the server send an email when there is an issue with the volume? Is there ...
5
votes
5answers
5k views

LVM mirroring VS RAID1

Having learned a bit about LVM mirroring, I thought about replacing the current RAID-1 scheme I'm using to gain some flexibility. Problem is that according to what I found on the Internet, LVM is: ...
4
votes
3answers
7k views

Slow parity initialization of RAID-5 array on HP Smart Array P411 controller

On 29th October 2011, I built a RAID-5 array using 4 x 146.8GB Seagate SAS ST3146855SS drives running at 15k connected to a PowerEdge R515 with HP Smart Array P411 controller running Windows 2008 (so ...
5
votes
1answer
1k views

Encrypted LVM on RAID1 - Failure testing, manual mount

We have an Ubuntu 10.04 LTS server set up with LVM running on top of disk encryption, which runs on top of a RAID1 volume comprised of two physical SATA disks. The configuration looks like this: ...
10
votes
3answers
8k views

Battery Backed Write Cache

I recently got some U server price quotes and some of them include BBWC: What exactly does it do? Is it just for RAID configurations? If there is a power malfunction, isn't the data loss ...
6
votes
2answers
7k views

Dell Perc 6/i and 3TB drives?

Does the dell Perc 6/i controller support 3TB drives?
2
votes
1answer
4k views

Installing Ubuntu 12.04 on HP Proliant DL380e with 1TB SAS Drive

I have an HP Proliant DL380e with a 1TB SAS Drive and I am trying to install ubuntu server 12.04 on it. I have created a RAID array using Array Controller Utility and had a RAID0 logical volume ...
5
votes
1answer
986 views

HP Proliant ML350 G5 SAS HDD

I am getting problem in HP Proliant ML350 G5. Some few days back one of the SAS HDD failed. It was 146GB SAS 15krpm HDD. We got new one which is 146GB SAS 10k rpm HDD. Its on RAID 1(1+0) ...
5
votes
4answers
2k views

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 ...
4
votes
1answer
2k views

Accidentally deleted wrong logical drive HP Smart Array P800 controller

I was tasked to do some rearranging on my company's HP Proliant storage server. In the p800 configuration utility I managed to delete the wrong logical disk, which was a 10 disk RAID 6 array. I'm just ...
1
vote
1answer
514 views

Remote RAID Control in ESXi on a Dell PowerEdge 2950 Using OpenManage

I was wondering how one can add a drive into an existing RAID array while ESXi is still running. I have read that you are able to use Dell OpenManage to do this. I have installed OMSA 7.0 on the ...
1
vote
3answers
1k views

HP DL585 G1 with VMware ESXi 5 - SATA solution, need more storage

I have the following: 2 x DL585 G1 (8 cores) with built in Smart Array 5i (2 x 74GB SCSI in Raid 0) I installed VMware ESXi 5 and got it all working :) However I need more space. I was thinking ...
16
votes
8answers
1k views

Optimal UNIX File System Partition + Setup Strategy

When partitioning a new system disk(s) for UNIX, what is your prefered strategy for both desktop and/or servers? Please include disk partition layout, file system format(s) and options, mount points, ...
25
votes
5answers
2k views

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 ...
2
votes
1answer
19k views

Dell PowerEdge - Add new disk to an existing RAID 5 array

I have a Dell PowerEdge with a RAID 5 array of 3 disks, and I want to add a fourth disk to it to expand the capacity of the volume. I don't want to reinitialize the whole RAID 5, because I want to ...
2
votes
4answers
1k views

Can I “atomically” swap a raid5 drive in Linux software raid?

One of the drives in my 3-disk raid5 array is starting to show read errors and SMART warnings. Not enough to get it kicked out of the array (as faulty), but it affects performance and will probably go ...
7
votes
6answers
41k views

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. ...
5
votes
3answers
4k views

RAID 5 with big SATA disks. Do or don't?

Is it sane to build a machine with RAID 5 expecting to hold around 5 Tb (and able to grow) with 1.5 or 2 Tb SATA II disks? It will be used as audio and documents storage. I already have chosen a ...
1
vote
4answers
16k views

How can I un-mark a partition as active?

Overview: I use a backup storage enclosure with 6 backup drives incrementally backup up and taken off-site. One day I noticed that the backup process was failing. I logged onto the server that is ...
6
votes
1answer
1k views

Does ZFS replace the need for hardware/software RAID?

I want to provide protection against data loss on my servers. Typically, I'd use hardware RAID 1 or 5, but I've been reading up on ZFS. Is it correct that ZFS itself provides RAID 1 or 5 like data ...
6
votes
1answer
7k views

Boot from software RAID 1 on Windows Server 2008 R2

I have a Windows Server 2008 R2 x64 system with a single hard drive, and I have a spare hard drive of same size/model that's not being used. I was thinking about dropping in the new drive and setting ...
6
votes
5answers
2k views

What is the best way to configure 6 disk raid for SQL Server + OS?

I'm setting up a SQL Server on Win 2k8 with following hardware: 6 x WD RE3 500G SATA PERC H700 I've read some suggested that putting log file and OS on its own RAID1 while the rest of data is on ...
5
votes
3answers
6k views

Can I convert a 1 disk RAID 0 to RAID 1?

This is dangerously close to question 18957, but it isn't quite the same. One of my logical drives on my P410i is a single disk RAID 0 (because I was short sighted at the time). It's now warning ...
4
votes
1answer
339 views

How to recreate a RAID 10 array with mdadm

So our virtual machine has broken (it's actually a Linux machine in Azure) on which we were running a RAID10 array of 4 disks. It's an ubuntu box. From what I can tell the four data disks are fine, ...
3
votes
2answers
2k views

Monitor LSI 3ware raid controller on ESXi

This concerns a server that runs ESXi (v. 4.x or 5.x) installed on drives that are configured into a raid10 using an LSI 3ware 97050 raid controller. I would like to know if there is a way to monitor ...
3
votes
8answers
1k views

Deploy Xen

I would like to deploy Xen virtualization, however I definately not sure which way to go. Citrix Xen Server has (AFAIK) better managment tools, but does not provide software raid. Ubuntu / CentOS ...
1
vote
1answer
65 views

Disabling damaged RAID 1 to read from healthy HDD

One of the HDDs in my software RAID 1 on a dedicated server is damaged. The customer support is slow to respond. I would like to transfer all data I need to another server, but file access is ...
0
votes
3answers
2k views

3WARE 9650-4LPML JBOD DISK to RAID - 1 Mirror Migration How To?

It is possible to migrate a single disk, to Raid 1 as per Table 10 in the User Guide Page 122: http://www.3ware.com/support/UserDocs/3ware9650SE-UsrGuide.pdf I am trying to find what the best method ...
10
votes
7answers
645 views

Can a RAID 4 disk setup crash if only 1 hard disk fails? [closed]

I am a web developer. I have not much experience in hardware. For this reason, I use managed servers. This morning, one of the drives in our setup failed. However, the full site went down. I ...
5
votes
2answers
31k views

HP SmartArray P400: How to repair failed logical drive?

I have a HP Server with SmartArray P400 controller (incl. 256 MB Cache/Battery Backup) with a logicaldrive with replaced failed physicaldrive that does not rebuild. This is how it looked when I ...
4
votes
2answers
351 views

RAID 5 detects write errors?

I have seen people recommend RAID 10 over RAID 5 for databases due to RAID 10 giving better performance and a better chance of recovering from a hardware failure. This confuses me as I thought the ...
3
votes
2answers
703 views

What are the recognized ways to increase the size of the RAID array online/offline?

Is it possible, in theory, increase the size of the RAID-array of any level just by adding new drive(s)? Variant like "backup whole data -> delete old array -> add/replace disks -> create new array -> ...
3
votes
1answer
4k views

How do I migrate disks from one Dell PE 2850 to another?

I had a Dell PE 2850 die and I need to move its SCSI disks over to another PE 2850. These disks were in RAID1. I tried moving them over and just hoping the PERC would do the right thing, but it ...
1
vote
2answers
333 views

Proliant raid controller in a PC

Does anyone know or have experience installing an HP array controller in a standard PC? I'm interested if it would be possible to use a P400i with a SAS-SATA cable using standard Western digital ...
1
vote
2answers
6k views

HP ProLiant ML350 G6: Does the RAID rebuild automatically?

One of sas hd of this ML350 died... We're buying a new one and I wanted to ask if I can just take out the faulty one and insert the new one with the server on to let it rebuild the raid or I'm forced ...