Hard Drive Help

[airking95]

Hi, I am planning to make a new rig for my PC, and I want to buy 2 x 2 TB HDD's run them in RAID 1,and 2 X 4TB HDD's also want to run them in RAID 1. What would be a good hard drive to buy for that storage solution, WD Red, WD Black, Barracuda ? Also, I am the only one that uses that data inside, so would it be better to use a NAS for this solution, or just a normal setup inside the PC?

[Akolyte]

You will get more bang for your buck with a Barracuda, but I advise WD Reds they are designed for Raid configurations and should be stable.  However, they will be slower.  I would advise a NAS, just because having this much storage in your PC makes it hard to manage and you expose it to security threats and other stuff.  As just having lets say an ssd and a 1TB hard drive in your machine and having a whole NAS to backup to would be much better.

[airking95]

Ohh, alrite but a NAS would cost me $200 more, is it still worth it ?

[Ahnzh]

a nas is made to be running nonstop, having power consumptions of 10w idle to 30w while being under full load. Computers usually have like 150W while in idle. it's a difference of 120w -> 0.12Kw/h -> roughly 1050Kw/h a year

 

1 Kw/h is like 25 euro-cents in germany, so 0.25€, makes a cost of 250€ per year that i save by running a NAS instead of a Computer nonstop. That's under full load vs idle. That's the worst case scenario.

 

200 Dollars a year should be a good estimate of what you save. Worth it? i would say, yes. Even if you are working with your pc a lot and it's active half the time you profit from it.

[airking95]

Oh alright, by the way I want to use RAID 1 because in the past this year, I have lost my data by the drive dying on me, and I don't want to lose my data againg. so would RAID 1 be a good solution for this ?

[iExpurge]

2x4 and 2x2 in raid 1 leaves 6TB of usable space. so why not get 4x3 in raid 1? that also leaves 6 TB and should be cheaper. But by far the most important question is what data is this? Are they just movies and game saves? or are there family photos on it?

Because RAID 1 is NOT a backup. It delivers more safety than a single disk but its not nearly as safe as a physically separate (preferably offsite) backup.

[Ahnzh]

RAID 1 is awesome for data security. but keep in mind: a 4 TB Seagate NAS HDD costs 155€, the 3 TB version costs 115€. So you almost can get 3 3TB for the price of 2 4TB with Raid5 as an option and 6TB usable instead of 4TB. 

[Ahnzh]

2x4 and 2x2 in raid 1 leaves 6TB of usable space. so why not get 4x3 in raid 1? that also leaves 6 TB and should be cheaper. But by far the most important question is what data is this? Are they just movies and game saves? or are there family photos on it?

Because RAID 1 is NOT a backup. It delivers more safety than a single disk but its not nearly as safe as a physically separate (preferably offsite) backup.

?????????

 

 

2x4=8 or 4 in raid1, 2x2=4 or 2 in raid1, 4x3 raid1=3

 

raid1 no backup/security. hmmn kk. 

 

what did i just read

[iExpurge]

How do you not get this? raid 1 means that for every disk there is another one with the exact same data on it effectively halving the amount of net storage.  So 4x2=8 and 2x2=4   (4+8)/2=6TB net storage.  4x3=12 12/2=6TB net storage. 

And with raid 1 if the computer dies, you still lose your data. Its not the same as a backup. Its fine for stuff that's important, but not as important as family photos.

 

So ill ask again how important is this data ?

[Ahnzh]

How do you not get this? raid 1 means that for every disk there is another one with the exact same data on it effectively halving the amount of net storage.  So 4x2=8 and 2x2=4   (4+8)/2=6TB net storage.  4x3=12 12/2=6TB net storage. 

And with raid 1 if the computer dies, you still lose your data. Its not the same as a backup. Its fine for stuff that's important, but not as important as family photos.

 

So ill ask again how important is this data ?

ok i see your point now, my mind blanked it seems. i thought airking95 was talking about either a 2x2 OR a 4x2 raid, not both, so the 6TB threw me off. sry for the confusion.

 

But it's not entirely correct that you lose your data if the computer dies. That's the main reason you don't want to run the raid off the onboard chip. You want to use a software raid because the raid data is stored on the HDDs then, not on a chip, and is recoverable from every system that runs the same OS in the blink of an eye. Unrecoverable error rates are a larger threat in that case but with TLER/ERC it should be okay.

 

Then again +1 for a 3x3 or 3x4 RAID5

[airking95]

The data mostly consists of movies, music, games, etc. Nothing that is really really important such as documents and such.  

 

And I was wondering how does RAID 5 work, I know that if you have 3 drives, 2 are used for storage and the third is reserved when one fails, so everything can be copied onto the reserved one, but if the drive fails how is it copied on to the reserved one ? Also what happens when two drives fail ?

[Ahnzh]

think of raid5 as a raid0 with 'parity'

 

that means you got a file. this file is split in parts, that get distributed over the various HDDs. For example you got 3 drives, which means that the file is split into 2 parts, one part is saved to the first hdd, the second part is saved on the second hdd. then your cpu calculates a parity file which is saved on the third HDD. it serves the purpose of being able to restore the file if a drive fails. that means you can restore the file with a parity and one part of the file. If you add more drives, let's say 5 HDDs, you split the file into 4 parts and generate a parity as well. To restore the file you have to have 3 parts and the parity. If the parity drive fails it's not relevant since you still have the complete file. It's unlikely though that 2 HDDs will fail, but if that happens you lose your data.

Then again, having a RAID1 with 2 drives and 2 drives fail will result in data loss as well... ;D There is no 'reserved' HDD but you can add HDDs as 'spare' HDDs. Those spares are used for rebuilding the RAID. 1 Drive fails and the spare is used for starting to generate the missing data on it directly. This way you don't have to plug out the failed HDD and put in a working one to start the rebuild. This is used for large RAIDs though where you have like 16 or more drives. HDD failures are far more common then. You might lose one hard drive in like 2 or 3 years with 3 HDDs but that's it. Having a spare built in will just result in a waste of money.

 

 

If you are going to do a RAID5, pay attention to your drives having some sort of error correction. That's needed to avoid having a rebuild fail. For example 1 drive fails. you attempt to rebuild the RAID. A data package on one of the remaining drives is damaged. Without error correction the rebuild fails because the HDD tries to read the data and takes longer to do it but the RAID controller gives HDDs like 7 seconds to read the data. If they fail to do so the rebuild fails and you would lose your data. Error correction communicates with the RAID controller and asks him for help. This makes it possible to run complicated rebuilding methods by the HDD and the RAID controller working hand in hand. In case they cannot rebuild it they might rebuild the rest of the RAID and you just lose 1 file.

 

WD's error correction is called TLER, Seagate uses the term ERC, but it's the same in general.

[airking95]

hmm , so will I need a dedicated raid card for a setup with 4 X 3 TB running in RAID 1 on a NAS ?

[Ahnzh]

like i said, you don't... 1. you got ports on your motherboard, if those aren't enough, look for a HBA (Host Bus Adapter). Then set up a software RAID. Dedicated RAID cards are expensive. they have a controller on it that handles the RAID itself. In case of a software RAID you let your CPU handle the task instead. Easy job for it, so you just need enough ports.

[airking95]

But you would need one for 3 X 3 TB running in Raid 5 right ?

[Ahnzh]

you can use SOFTWARE raid. it's not a raid card. you boot your computer and set up a raid with a program that's usually integrated into your operating system. Just plug in the drives as separate drives and tell your Operating system to handle them as a RAID. As long as you have enough SATA slots on your Motherboard you don't need a hardware RAID card. 
 
from Wikipedia:
 

Many operating systems provide basic RAID functionality independently^{[clarification needed]} of volume management:

• Apple's OS X and OS X Server support RAID 0, RAID 1, and RAID 1+0.^{%5B31%5D%5B32%5D}
• FreeBSD supports RAID 0, RAID 1, RAID 3, and RAID 5, and all nestings via GEOM modules and ccd.^{%5B33%5D%5B34%5D%5B35%5D}
• Linux's md supports RAID 0, RAID 1, RAID 4, RAID 5, RAID 6, and all nestings.^{%5B36%5D%5B37%5D} Certain reshaping/resizing/expanding operations are also supported.^%5B38%5D
• Microsoft's server operating systems support RAID 0, RAID 1, and RAID 5. Some of the Microsoft desktop operating systems support RAID. For example, Windows XP Professional supports RAID level 0, in addition to spanning multiple drives, but only if using dynamic disks and volumes. Windows XP can be modified to support RAID 0, 1, and 5.^%5B39%5D Windows 8 and Windows Server 2012 introduces a RAID-like feature known as Storage Spaces, which also allows users to specify mirroring, parity, or no redundancy on a folder-by-folder basis.^%5B40%5D
• NetBSD supports RAID 0, 1, 4, and 5 via its software implementation, named RAIDframe.^%5B41%5D

[Almercenary]

WD red for Raid setup, I think that's what they were designed for, or at least serious nas setups.

[Ahnzh]

WD red for Raid setup, I think that's what they were designed for, or at least serious nas setups.

i prefer Seagate NAS HDDs. Bad experience with Reds