RAID stands for Redundant Array of Independent Disks.

RAID is data storage technology that allows multiple drives to be used together as a single virtual drive for reasons such as fault tolerance, reliability and performance.

There are several different levels of RAID that determine how the data is stored and the level of redundancy achieved across the drives.

Share tech news, updates, or what's on your mind.

Sign up to Post

We are redesigning out current ZFS file server. It currently only has one pool of over 70TB.

I see this is a problem since, if there are enough disk failures within the pool to make it non-functional, we have to restore all 60TB of currently existing data.

A debate has risen as to how to divide up the storage into smaller pools, and how big/small each of those pools should be.

As I see it, the only drawback of using pools that are "too small" is a lot of wasted disk space. We are using `4TB 7500 spinning disks` with `4TB SSD cache disks`. So, I'm leaning towards 20TB raidz vdisks.  That means we get about 77% of the disk space usable.

Q: Are there any other advantages/disadvantages to making the pool sizes too large/too small?
Build an E-Commerce Site with Angular 5
LVL 13
Build an E-Commerce Site with Angular 5

Learn how to build an E-Commerce site with Angular 5, a JavaScript framework used by developers to build web, desktop, and mobile applications.

776 (Ready for Recovery) Logical Drive 1 (1.4 TB, RAID 5) is queued for rebuilding. hp server g5 ml350 server has been in this state for 2 weeks server has been restarted still says ready to rebuild not sure where to look next thanks
I have a PERC H330 card and would like to build an 18TB raid 5 array out of four HGST 6TB SAS disks. Two disks are 512b, 6Gb/s and the other two 4KB, 12Gb/s.

For some reason though I cannot add them into the same array. They work in separate raid 1 arrays but that isn't what I want.

Is it perhaps the case of an old firmware version on the PERC card (4.290.01-8335) or I simply cannot combine the two types of disks together?
Hello all,
I'm configuring an HP Z420 workstation with a 1TB SSD system drive (Boot /OS Drive) and two Enterprise 4TB SATA HDD for storing all my data in RAID1 . I wanted to know what the best RAID1 configuration would have the best performance for how I will be using it.

I mostly will use the workstation for document editing (word, excel, PDF, PowerPoint, Visio, etc.), internet , watching videos.

I plan to store A LOT of personal photos (thousands) in RAW format (each can be 15MB to 40MB) on the 4 TB RAID1.  I do some minor photo editing on photos using Google photos and I also store personal video files as well. I rarely edit videos and they are usually no more than 15min long but I do have a few longer than 1hr.

The workstation has the following RAID CARD:
LSI Logic SAS9260-8I SGL -8PORT, Int 6GB SAS/sata,  Pcie 2.0, 512MB RAID Card WITH a battery backup on the card itself. I also have a UPS for the computer as well.

The RAID configuration page has the following options (Image attached):
- Raid Level (I chose RAID 1)
-Stripe Size ( the options here are- 8kb, 16kb, 32kb, 64kb, 128kb, 256kb, 512kb, 1MB)
-Access Policy (RW is the default)
-Read Policy (options here are- Normal or Ahead)
-Write Policy (I chose Write Back with BBU since I have the Battery backup unit but other options are Write through, Always write back, write back w/ BBU)
-IO Policy (Options here are- Direct or Cached)
-Drive Cache (Options here are- NoChange, Enable or Disable)
I have a desktop computer (Alienware) with four internal hard disks, with a RAID motherboard.  Two of the disks are striped (the c:\ drive) and the other two disks are mirrored (the d:\ drive) and contain all my data.  The c:\ drive contains my operating system (Windows 7) and all my programs.  I want to replace the c:\ drive disks with 2 SSDs.  I want to clone the c:\ drive and then transfer this clone to the 2 SSDs, which will constitute the new striped c:\ drive.  I have cloned and transferred an old hdd's content to a new SSD, but without RAID.  It was easy.  But how do I do the same with a RAID system?  I'm at a loss as to how to proceed.  

Thanks, WmABradnan
I am looking to build a cheap storage device using a DELL perc H330 PCIE RAID adapter and a few HGST 6TB SAS disks.

I tried using a couple of older (6+ years) desktop motherboards but neither of them would allow the RAID controller as a boot device.

Can you please recommend something relatively cheap that's proven to work in this scenario? UK market preferrably, can be second hand.
Hello everyone.

For starters, I do not make a lot of money in my self-business.
So, I have to get what I can get, in order to grow.
With that said.

I have just purchased an Intel SR2500ALBRP
The motherboard: S5000PAL

In the following image, you will see a BLUE set of SATA cables with a single PLUG at the end.
Intel SR2500ALBRP RAID SATA Connector
Now, The PCI riser assembly has only a NIC Card on it with DUAL 1G nics.
My question is simple.
WHAT RAID Card do I need to get, to connect this with?

We have an MD3200 for storage in our HYPERV cluster.  We used the wizard to create a pool on the MD3200 which seems to have set aside 2 disks for redundancy (basically, a RAID 6, I believe).

I create a virtual disk in the pool, I wanted to use up all the available space.  However, the MD3200 starts complaining about > 80% (I believe the default) of the pool being used up.  Can I just turn that off or do I truly need to ensure the virtual disk takes up less than 80% of the space of the pool?

Hi, I have an odd question that would like to know what others are doing these days.  I know keep doing the same thing because that is they way it has always been done, isn't the best choice.

I am setting up a RAID 1 array on a HPE ProLiant DL360 Gen10 server with Smart Array P408i-a.  In addition, I have 3 HPE 300GB SAS / 12Gb/s HDD's.

So, my intent is to setup a RAID 1 array with a hot spare.

This will be supporting a Windows Server 2016 - Standard domain controller.

With all that being said, what strip size would you use in this scenario?  64KiB?  128KiB?  256KiB?

Currently, the default is 256KiB.

Just curious.

Thanks in advance.
I can't get one of my servers to power up. I don't believe it's a hard drive issue, more importantly for the sake of this question, I don't believe it's a hard drive issue. How do I recover data from the RAID?
Ensure you’re charging the right price for your IT
Ensure you’re charging the right price for your IT

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden using our free interactive tool and use it to determine the right price for your IT services. Start calculating Now!

RAID levels 0 and 1 can be combined to make a stripe of mirrors (RAID 10) or a mirror of stripes (RAID 01) configuration.  Which implementation would you prefer to use and why?
Dear Experts

I have a question related to controller M1015. I want to use it in IT mode for Unraid server.

In specification I can read this:
The ServeRAID M1015 SAS/SATA Controller has the following specifications:

Eight internal 6 Gbps SAS/SATA ports
Supports SAS and SATA drives (but not in the same RAID volume)
Two Mini-SAS internal connectors (SFF-8087)
6 Gbps throughput per port
LSI SAS2008 6 Gbps RAID on Chip (ROC) controller
x8 PCI Express 2.0 host interface
Supports RAID levels 0, 1, 10 (RAID levels 5 and 50 with optional ServeRAID M1000 Series Advanced Feature Key)
Connects to up to 16 SAS or SATA drives
Supports up to 16 logical volumes
Supports LUN sizes up to 64 TB
Configurable stripe size up to 64 KB
Compliant with Disk Data Format (DDF) configuration on disk (COD)
S.M.A.R.T. support

What I do not understand is - does this controller allows to connect 16 physical SATA drives? If yes why it reports only 8 internal ports?

many thanks for your advice

Good day,
We have a VM host that runs two server machines.  The first is the DC/FS and it works great.  The second machine is a terminal server.  It constantly is freezing on the users and it is getting frustrating.  Here is some info:

Host machine is running Server 2016 Standard.  Its specs are:

HPE Proliant DL380 G9
Xeon E5-2620 v3
RAID 10 for the virtual disks

Server is stable, no issues.

The host machine allocates a large portion of RAM to the DC and the TS.  The DC currently has 8GB and 8 virtual processors.  The TS has 10GB RAM, and also 8 virtual processors.  Originally I had the TS with less RAM and processors, but in trying to fix the freezing issue, I increased the resources.  I plan on bringing them back down.

The TS has only 3 users signing in.  They use the same domain account to log in to the server.  The TS is configured to allow the same user to log in multiple times.  It is light usage.  The TS exists to run only one program.  While using that program, the users may open Word or Adobe, but not much of anything else.  About 4 or 5 times a day, the server just stops responding to that user.  The other users logged in do not experience the same.  It will just spin and spin.  The remote connection never breaks.  Frustrated, they just click the x on the top blue ribbon, and re-log back in.  Then its totally normal until it freezes again.  

During the freeze, the internet is working normally, the others users aren't affected.  A VPN …
Probably a fairly "classic" issue but I have surprisingly not found definitive info about it online.

What is the best practice managing hardware RAID controllers on ESX Hosts ? Ideally, we would like to be able to "reach out" to the controller from a Windows guest VM but if not possible at the very least have some management capability (expand RAID, check array consistency) from ESXCLI.

How should we go about it ? In our specific and immediate case ESX6.5 with Intel RMS25CB080 controller.
Can i convert a mdadm from raid 6 to raid 0

I have a machine with 10&10TB of data in raid 6.

I'm looking to convert to Raid 0

I dont really care if I lose the data (I have several copies) I just would prefer daving the time off wiping machine - raid 0 - then transferring it all back again.

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdc1[2] sdi1[8] sdf1[5] sdj1[9] sdh1[7] sde1[4] sdg1[6] sdd1[3] sdb1[1] sda1[0]
      4190208 blocks super 1.2 [10/10] [UUUUUUUUUU]

md1 : active raid1 sdc2[2] sdi2[8] sde2[4] sdj2[9] sdg2[6] sdf2[5] sdh2[7] sdd2[3] sdb2[1] sda2[0]
      523712 blocks super 1.2 [10/10] [UUUUUUUUUU]

md3 : active raid6 sdc4[2] sdj4[9] sdi4[8] sde4[4] sdf4[5] sdg4[6] sdh4[7] sdd4[3] sdb4[1] sda4[0]
      75980845056 blocks super 1.2 level 6, 512k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
      bitmap: 2/71 pages [8KB], 65536KB chunk

md2 : active raid6 sdc3[2] sdg3[6] sde3[4] sdi3[8] sdf3[5] sdj3[9] sdh3[7] sdd3[3] sdb3[1] sda3[0]
      2110783488 blocks super 1.2 level 6, 512k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
      bitmap: 2/2 pages [8KB], 65536KB chunk
Hi I have to replace some SAS drives in a Power Edge, they amy SAS hard drive all in hot swapable carages.  The SAS connection is like the crummy pix I took, it has a single cable connection.  When I go on Amazon to get a SAS drive, the pix all show they have the SATA connections.  I don't know if they are mis labeling their parts, or just use the same pix as the normal drive.

Also, I thought that SAS drives were either 10k or 15K RPM, these are showing up as 7200 RPM.  

Thanks all.
Physical Disk 0:0 was replaced. There was an option to make it part of a RAID and once I selected that option the "State" immediately went to "rebuilding".
I look at this 3 days later and this is what I see:
Physical DisksHovering over either triangle shows Status: Non-Critical
The only available tasks for disks 0 and 1 is offline
There are no other tasks listed for disk 2 (just shows Available Tasks) or disk 3 (just shows No Task Available)
I inherited this server. It is set up in a RAID 10... not sure which disks belong to what though
RAID 10I think my first concern is disk 0... then the foreign issue with disk 3.

I have purchased a Qnap server QNAP TS-1283XU-RP 12 Bay  with 96TB (12 x 8TB Seagate EXOS enterprise class SATA HDD 7200RPM)

We are using VMware  and I would like to use this for onsite backup, for backing up our Virtual servers using Veeam backup and backing up user files using BackupAssist software with  this Qnap server as a backup target.

Please let me know the Raid type that i need to set up.
On this Qnap server , It gives me the Raid option of Raid5, Raid 6, Raid10

For Raid 5 With 1 hotspare, it gives a usable space of 72TB
For Raid 6 With 1 hotspare, it gives a usable space of 65TB

I dont want to go for Raid 10  and it ask for 2 spare and the usable space is only  36TB

I am not very keen on the performance of the qnap and it is only for the Veeam Back up target and File server Backup target.

Please suggest , the suitable Raid ( RAID5 or RAID6) that i can set up and your help much appreciated.

I have decided that Surveillance vs. NAS hard drives are more about marketing and not much at all about technical spec's.
Do you agree or are there technical differences worth mentioning?
I've looked but not found.

I'm interested because I'm about to set up some file server drives that have pretty modest demands re: speed.
So, I don't know that rpm matters all that much and it appears that cache sizes are the same.
I'll likely put in 10TB drives in RAID 1.
C++ 11 Fundamentals
LVL 13
C++ 11 Fundamentals

This course will introduce you to C++ 11 and teach you about syntax fundamentals.

I am currently running a pretty beefy system so this question is purely for my general know. Just messing around really.

I am running Windows 10 pro.

So my OS drive is a Raid 0 1 TB nvme configuration. Yes, I back everything up to multiple locations.

Now my question is, is there a way to take my storage drive and use a portion of the nvme (or another SSD) as cache?  Just to speed up frequently accessed files.

Just curious. Thanks in advance.
I have a Dell R220 Server running Windows 2012 with a PERC H310 Adapter
The server had 2 x 2TB hard drives in a RAID 1 array
We have replaced the drives with 2 x 8TB drives

Replace Disk 0:1 with 8TB drive
Boot into OS and launch Open manager
On the Physical Disk windows, select the available task to convert to RAID type disk
On the Virtual Disks Page, select the available Task to replace Member Disk
Select Disk 0:0 as source and 0:1 as destination.
Wait for Rebuild to complete

Replace Disk 0:0 with 8 TB drive
Repeat process as above but choose 0:1 as the source and 0:0 as the destination
Rebuild now complete

Within the Physical Disks page, Physical Disk 0:0 shows as Online with no available task
The properties of disk 0:0 show
Capacity 7,451.00GB  
Used RAID disk space 1,862.50GB,
Available RAID Disk Space 5,589.00GB

Physical Disk 0:1 shows as Ready with available tasks to Assign Global Hot Spare or Convert back to non-raid. The properties of Disk 0:1 are
Capacity 7,451.00GB  
Used RAID disk space 0.000GB,
Available RAID Disk Space 7,451.50GB

The Physical Disk page shows State Degraded, Layout RAID-1, Size 1,862.50GB
Available Tasks are Delete, Assign/Un-assign Dedicated Hot Spare, Rename, Change Policy and Replace Member Disk.

The Raid has obviously worked as it replicated the drives both times and in the Windows Disk Management console the Drive shows as one drive so all good there.

I am still left though with only …
I have configured the server to raid 5 all of the SSD disks in the server so in total there is 7tb available according to the config software. When I installed ESX6 (on a USB), it completes the install and I'm then able to log into the host via a browser. When I try and configure the datastore, it only sees the individual SSD disks and not the array. I can select any one of them but that is not what I'm after, I want the entire datastore to use all the disk. Im not able to select more than one of the disk so something is not right with the config of the HP onboard array interface.cleae test

The onboard controller is a Dynamic Smart Array b140i RAID
Hi I have a Dell Perc 740p RAID card I just put in a computer, the computer recognizes it but I can't get in with ctrl + R.  I see the post message, but this one dosen't say press ctrl + R to get into Bios.  it says...

"PowerEdge Expandable RAID controller BIOS copyright AVAGO Technologies"

Then Initializing virtual drives, then goes on it's marry way.

Question: is there another way to get into Bios?  Am I dooing something wrong?

Thanks all
Our domain servers are working on VMware Workstation virtual machine. Recently we decide to move them to ESXi 6.5 that's installed on DELL R720 and T30. But the problem is ESXi cannot manage RAID disks. I installed MegaRAID on ESXi, however it only can monitor status, and I can't find the function to schedule check and report disk status. I also bought a LSI SATA+SAS Host Bus Adapter with RAID Controller and install it on T30, but I still need to reboot then access RAID control page to create/change RAID.

Is there a program based on ESXI to let me manage, control RAID disks without shutdown ESXI? Or at least I need a program to check disk status and email me the check result.

Thank you very much for any suggestion.
we have an Azure backup system fro our server.  We have had 2 hard drive failures on a raid 5.  I have managed to get the server up and running by reinstalling server OS.  the problem now is getting the backup vault and software installed in order to get the data from the backups.  Can some please help?


RAID stands for Redundant Array of Independent Disks.

RAID is data storage technology that allows multiple drives to be used together as a single virtual drive for reasons such as fault tolerance, reliability and performance.

There are several different levels of RAID that determine how the data is stored and the level of redundancy achieved across the drives.

Top Experts In