Why is unRaid better than Windows Home Server (WHS)?

[krackato]

I'm pretty excited about unRaid, but my friend asked me, "Why don't you just install Windows Howe Server?"

 

Other than a YouTube clip that basically said WHS was terrible, I'm not sure why.  My friend uses WHS and he loves it.

 

So why is unRaid better than Windows Home Server?

[BRiT]

unRAID is more efficient at offering data protection. In the situation where you want data protection, WHS runs in a RAID-1 like scenario, while unRAID runs in a parity protection scenario.

 

I wont go into the nitty gritty technical details right now, but this should provide for a general overview of what many see as the main benefits.

 

CAVEAT: This is based on how I understand WHS to function. This may not apply to the next version of WHS which is currently in early alpha testing.

 

Lets assume you want all your data to be protected and have 4 drives (all the same size for simplicity sake):

Point 1

*) WHS effectively can only use 2 drives for data storage since it uses the remaining 2 drives to mirror the data.

*) unRAID effectively can use 3 drives for data since it uses 1 drive to store the parity information.

 

Point 2

*) WHS will have all the drives running if even 1 drive is being used

*) unRAID will spin down individual drives not in use

 

Lets extend this a bit more to a 20 drive array so you can easily see the benefits

Point 1

*) WHS effectively can only use 10 drives to store data, the other 10 are for data mirroring.

*) unRAID effectively can use 19 drives to store data, the other 1 drive is used to store the parity information.

 

Point 2

*) WHS will have all 20 drives running when reading the data.

*) unRAID can spin down the other 19 drives when reading the data off a single drive.

 

[boof]

As above WHS uses raid-1-esque duplication of files on a per share basis. You can enable this for individual shares.

 

This means protecting data within that share takes up twice the disk space.

 

Unraid protects everything all the time using a single disk of parity.

 

You will effectively get much more usable disk space using unraid than you will with WHS and you wont have to worry about individually deciding which shares you do or do not want redundancy on as with unraid everything is always protected. (cache drive and drives outside the array withstanding)

 

Both WHS and unraid will spin down idle disks.

 

Other than that the obvious difference is unraid runs under linux from a ram disk (booted from USB) and WHS is pretty close to being windows server 2003 and runs from a 'normal' partition on a hard disk.

 

I wouldn't necessarily say either is better than the other - they're just fundamentally very different in their approach to data protection. Whichever one suits your requirements best.

 

I'll have to go look for info on the new version of WHS...didn't realise there was an alpha!

[guiri]

 

If unraid has ONE parity drive, what if THAT one fails?

 

George

[neilt0]

 

If unraid has ONE parity drive, what if THAT one fails?

 

George

 

You replace it with a new one and build parity. You won't lose data.

 

If one data drive fails, you replace that and rebuild it using parity -- no data loss.

 

If you have two drives fail simultaneously, the most you will lose is the data on those two drives.

 

There has been discussion of implementing a second parity drive (Q-parity), which is useful for systems with a large number of drives. Like mine.

[barrygordon]

The technology that unraid uses allows any single drive to be completely rebuilt when there is a failure (partial or complete) of that single drive. This includes the parity drive.  If you are unfamiliar with the methodology I will try and explain it.

 

Imagine all the bits on a drive lined up one efter another (left to right) with the most significant bit of the first byte on the drive on the left although it does not matter.  Lets call this a row. This row is pretty long for large drives! Imagine now that there are N rows where N is the number of drives including the parity drive. If we now look at this array (matrix) all the corresponding bits of all the drives are lined up under each other.  Lets call this a parity column.

 

Lets adjust the data on one of the drives, lets make it the top row, such that an exclusive "OR" of all the bits in a parity column produces a "0" (zero) .  The array now has parity set. If any drive has a recognized failure then parity for each parity column across the entire array can be recomputed without using the failed drive in the parity computation. The result of that computation can be stored in that parity column of the failed (or new cleared) drive returning the entire array to its "Parity Corrected" state.

 

Hope that helps 

[Rajahal]

unRAID also has lots of user created add-ons and scripts that allow you to customize and tweak your server.  There's even an add-on for WHS!

 

Use unRAID for a while, and your friend will probably want to convert his WHS out of unRAID envy

[lionelhutz]

Beyond the parity drive protection, I just like unRAID for it's simplicity. No OS to install and get corrupted. You effectively re-install the OS every time you reboot the server. You can create a flash with the free version and have unRAID running within about 10 minutes of the download.

 

Both have their pro's and cons. WHS being a Windows OS has some add-ons and other such things that are easy to install and use. unRAID can do much the same but it's not the simplest to use add-ons. Every Linux user has their own version of how to do an unRAID add-on while with WHS it's typically a single source program which can be much easier to use and understand but then it's also limited by what the source decides you need.

 

There was a thread here where the user had started to clear a data drive or something like that (even worse than just formatting) and with some help he still recovered most of his data.

 

Peter

 

[queeg]

I use unRAID.  I've never used WHS although I almost did.  

 

unRAID:

Good:

The fact that unRAID is booted from a flash drive really is very appealing to me.  It's simple, it can be backed up easily.  The most important reason I chose unRAID is that if/when the hardware fails it can be replaced with something else.  Different mobo, cpu, ram, whatever.  Just boot unRAID and maybe have to reassign data drives and then it's back up and running with everything exactly the same.

Bad:

While there are add-ons they are typically harder to install for a windows savvy person.  

There is limited hardware support.  It's a pretty darn good selection but still it's limited so check the list before you buy.

 

WHS:

Good:

Being a windows product it supports an enormous amount of plug n play hardware.  Tons of software can be installed on it and it's easy to install the stuff.

Bad:

The more you install on the thing the harder it will be to recreate if/when it fails.  When your motherboard craps out you will be reinstalling everything again, if you can even remember what you have installed.  Or you can keep a set of redundant parts on a shelf which costs money and who knows if the extra parts are doa unless you test them when you buy them which in itself is a major hassle.

 

 

[DavejaVu]

I recently moved from a WHS rig (HP MediaSmart EX470 plus 4-bay eSATA array) because of a few reasons.  The first was the RAID-1 aspect of it, where I was losing half of my space to duplication, rather than the parity drive idea that unraid uses.  The second was an issue of scale, where the system seemed to be struggling with 8 disks and would periodically check out for no obvious reason.  Finally, I had a disk that was showing SMART errors that i was monitoring and knew the drive was failing, but WHS remained blissfully ignorant of that fact right up to the day it died.  That's inexcusable in a storage array of any sort.  Since moving to unraid, I have more space, it's easy to manage, and completely stable.  Anyone want to buy a HP MediaSmart?

[krackato]

So when I write to an unRAID system, do I actually have to pick which of the 16 drives to write to, or does it just appear as a giant 10-20TB harddrive?

[BRiT]

You can do both, select the individual disk(s) or the combined share.

 

The former is known as disk shares and on the box are shown as /mnt/disk#/.

The later is known as user shares and on the box are shown as /mnt/user/.

 

The shares are very configurable, allowing to include or exclude particular disks and electing what placement strategy to use when writing to the combined share (fill up, most free, high water). Official Manual section: http://lime-technology.com/wiki/index.php?title=UnRAID_Manual#User_shares_2