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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144
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2answers
28k 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?
10
votes
2answers
22k 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 ...
85
votes
13answers
34k 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 ...
4
votes
2answers
5k 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 ...
26
votes
5answers
20k 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 ...
3
votes
3answers
6k 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.
9
votes
3answers
9k 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 ...
8
votes
5answers
30k 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
2answers
1k 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 ...
6
votes
3answers
9k 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 ...
33
votes
6answers
26k views

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 ...
48
votes
10answers
8k views

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 ...
23
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 ...
11
votes
2answers
2k 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, ...
2
votes
1answer
8k 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 ...
26
votes
5answers
6k 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 ...
7
votes
3answers
48k 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
16k 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
7k 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: ...
5
votes
1answer
2k 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: ...
4
votes
3answers
14k 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
2answers
59k 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 ...
17
votes
5answers
12k 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. ...
26
votes
8answers
5k views

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 ...
10
votes
3answers
11k 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 ...
5
votes
6answers
10k views

MegaRAID JBOD substitute

It seems that certain MegaRAID chips don't support JBOD (unfortunately). I've read online that to make these controllers act as a pass-through, I should configure the disks in RAID0. What RAID0 ...
5
votes
2answers
6k 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 ...
2
votes
6answers
7k views

Ubuntu installation can't detect hard drives

I'm installing Ubuntu onto a HP Proliant DL360 G7 server, which has a hardware Smart Array RAID controller that is not compatible with Ubuntu. HP say the RAID controller needs to be disabled in the ...
6
votes
4answers
3k 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 ...
5
votes
1answer
2k 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) configuration....
4
votes
1answer
5k 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 ...
28
votes
7answers
15k views

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.
3
votes
2answers
54k 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 ...
17
votes
6answers
65k 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. ...
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 ...
6
votes
5answers
5k views

RAID level confusion (MegaCli vs megasasctl output)

I'm utterly new to working with LSI MegaRAID controllers and I'm confused as to what RAID level I am actually running. My server is equipped with 4 disks, 4TB each and I would like to have them ...
6
votes
5answers
3k 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 ...
4
votes
1answer
4k views

How to over-provision an Intel SSD RAID Array via the Dell H700 PERC RAID Controller

I would like to set up a RAID10 array of 6 Intel SSD 320 SSDs, but over-provision them to enhance their performance and duration as per this PDF: http://cache-www.intel.com/cd/00/00/45/95/...
6
votes
1answer
2k 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
3answers
20k views

Moving a RAID array from one machine to another

I'm not too familiar with RAID arrays, but I plan on making a RAID 5 array for a fileserver. However, once I get the RAID running for a while, I have plans to move it to another machine (with ...
6
votes
3answers
11k 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 ...
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 ...
3
votes
5answers
15k views

Software RAID underneath ESXi datastore

I'm building an virtual environment for a small business. It is based around a single ESXi 5.1 host, which will host half a dozen or so VMs. I'm having some doubts regarding how to implement the ...
3
votes
1answer
684 views

SSD's in servers, best practice redundancy?

So some might say Im an experienced infrastructure architect guy and have been putting together server farms, storage subsystems and networks for a number of years in datacenter environments (...
3
votes
2answers
3k 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 ...
2
votes
1answer
6k views

HP RAID array - hpacucli

I've noticed that one of the drives has "unassigned" status. Does it mean that it's a spare disk? # hpacucli controller all show config Smart Array P410i in Slot 0 (Embedded) (sn: ...
1
vote
2answers
7k views

How to use SAS Expander with RAID card?

I've doing some researches since few days and I haven't really got an answer to my question. I am in the process of building a huge file server for the company I work for. We bought a server case ...
0
votes
1answer
58 views

Setup SunFire 440 Raid Configuration

How can I setup Internal Hard disk RAID5 configuration? I have SunFire 440 machine with 4 internal hard disk. I have never worked on Sun systems except for now and I am exploring google for the above ...
0
votes
2answers
5k views

data lost with RAID5 on proliant DL360 when drives fail

For some reason the Array Controller on my Proliant DL360 G6 couldn't recognize 2 of the 6 750GB drives I am running in a RAID 5 configuration with VMware ESXi 5.1. When I rebooted the server I chose ...
0
votes
3answers
3k 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 ...