RAID Pointless in a Home Media Server?

[taltamir]

That is why traditional filesystems are obsolete and filesystems like Btrfs and ZFS have a golden future. By checksumming your data you can solve the BER problem; ZFS is now virtually untouched by BER.

Also using 4K Advanced Format (EARS) drives can help, as these have a lower bit-error rate to begin with, though that doesn't translate in better specs. But specs say little honestly.

very true. I only use ZFS at the moment (btrfs is not ready yet)

JBOD is in every way shape and form vastly inferior to independent disks each formatted separately.
All it gives you is one logical partition, but if any of the drives on it fail you lose all your data, and you don't get any performance benefits.
RAID0 is actually better than JBOD, it is equally as unreliable, but at least its faster.

 

[Barnaby W. Füi]

This pushed me away from RAID 5 for forever:

http://www.zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162

Ah, good link. I seem to remember reading that a while back but managed to forget all about it. I hope btrfs stabilizes soon.

 

[sub.mesa]

Yes, though JBODs are easy to expand (just glue another device at the end) while RAID0s are not so easy to expand. So some embedded hardware RAID choose JBOD so user can start with 1 disk and expand easy to 4 disks for example.

But now we have ZFS we got something much better.
Enjoy!

 

[taltamir]

Yes, though JBODs are easy to expand (just glue another device at the end) while RAID0s are not so easy to expand. So some embedded hardware RAID choose JBOD so user can start with 1 disk and expand easy to 4 disks for example.

But now we have ZFS we got something much better.
Enjoy!

Independent disks are even EASIER to expand that JBOD... you just put the disk in, create a partition over the entire disk, and assign it a drive letter. (the above often happens automatically, so you just put it in and it appears on your PC).

 

[classy]

The use of raid is for redundancy and performance. Since neither of these are important to you then raid is pointless for your home media server. But most people don't want to redownload several gigs of data. And using any type of raid whether software or hardware in a raid 1 configuration will allow you to access the data without rebuilding the array.

 

[poofyhairguy]

And using any type of raid whether software or hardware in a raid 1 configuration will allow you to access the data without rebuilding the array.

That is actually one of my favorite things about Unraid- how well it works in "degraded mode." Take out a drive with a movie on it, reboot the system and play the movie like you never touched the drive. Its like magic to me, I have no idea how it works.

In fact, I don't get how any of these "one drive is parity for many drives" RAID systems work but this thread taught me the important of parity for my data....

 

[pjkenned]

Just a clarification: WHS is not a RAID 1 system. Instead it duplicates information across multiple drives. So if you have a copy of a file on drive A then there would be a second copy on drive C or E.

Now there is one huge benefit to WHS duplication over RAID 1, when a drive fails and is removed, duplication can occur in failed space. Let's say one copy of 1TB of data is lost in a WHS system with a remaining 4TB free. Duplicaiton can occur to that remaining 4TB meaning you get redundancy back before replacing a drive. That's a cool feature RAID 1 does not give.

Second, RAID 4/5 should be limited to 10 drives at a maximum. Even then I've seen single parity array failure rates to something like 20%+ in 3 years and go up from there. That's the big reason people don't use single parity for large arrays. Now for a 3-drive array, if you don't mind poor performance unRaid is not a bad option.

 

[classy]

Just a clarification: WHS is not a RAID 1 system. Instead it duplicates information across multiple drives. So if you have a copy of a file on drive A then there would be a second copy on drive C or E.

Now there is one huge benefit to WHS duplication over RAID 1, when a drive fails and is removed, duplication can occur in failed space. Let's say one copy of 1TB of data is lost in a WHS system with a remaining 4TB free. Duplicaiton can occur to that remaining 4TB meaning you get redundancy back before replacing a drive. That's a cool feature RAID 1 does not give.

Second, RAID 4/5 should be limited to 10 drives at a maximum. Even then I've seen single parity array failure rates to something like 20%+ in 3 years and go up from there. That's the big reason people don't use single parity for large arrays. Now for a 3-drive array, if you don't mind poor performance unRaid is not a bad option.

I am assuming that when you talk of WHS you are saying that in your hypothetical situation you have 5 1 terrabyte drives? I have never used WHS.

 

[pjkenned]

It wouldn't matter regarding the number of drives. You could have 10x 2TB drives with 4TB free and an average of 1.6TB on each drive (some would be lower some higher). If a drive fails you then have 18TB of installed capacity with 3.6TB free (assuming the drive that died had 1.6TB of information). That 1.6TB sits on the other 9 drives and would then be duplicated and distributed among the other 9 drives leaving 18TB installed capacity with 2TB free.

 

[theking7426]

I was looking in to the same thing the last couple days and came across this that made a large case for sticking to single disks if you are using consumer sata drives.

http://www.enterprisestorageforum.com/storage-technology/sas-vs.-sata-1.html

Basically it gives details about drive failure and that a normal sata drive should fail at about 10TB of transfer, in theory.
I am not 100% sure but it then goes on to explain that say 1 drive has a failure. Well the whole raid array must be rebuilt, which in turn, if it is a 10TB raid array that has lost a 2TB drive, means 8TB of writing, which could, in theory, take out another disk.

Basically it is not as big a problem with your 10TB array, but one it gets a bit bigger, a single failure will cause a loop of failures, eventually destroying all data.

Again this is what I understood from this article, so i guess make sure you go

Then again this post is likely irrelevant to all involved at this point.

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[dave_the_nerd]

Ok, before I start I know some of you will think I am crazy. I know as a computer geek my logic should be that RAID exists and for that reason alone I should use it.

But I have been looking to put together a new (probably Linux) media server and for the life of me I can't think of one good reason to use RAID.

Reasons I don't think RAID is worth it for me:

1. I am not buying my HDs all at once and I don't plan on just buying disks of all the same size for my server (I hope to go larger as large drives get cheaper), so it seems RAID 5 is useless to me.

Software RAID doesn't care.

2. I really don't care about redundancy. Not a single thing will go on my server that I can't just redownload/rerip, and the few things that would be a pain to redownload I am backing up on an external drive.

It's your life.

3. I don't like the idea of being at the mercy of software RAID (and I don't want to drop a few hundred bucks on a decent RAID card). I like the idea that if one of my drives (or my main OS drive) dies I can easily boot up a Linux Live CD and get at my data without having to rebuild a RAID and pray.

I think you have this backwards. A single HDD fails, that's it, you don't just boot from a rescue disk and magic happens. (Unless you're really lucky.) A degraded RAID array at least give you the opportunity to copy your data off of it before you pull the rebuild trigger.

4. The speed advantages given by some forms of RAID are not needed. I recently tested (on my desktop) streaming 30GB+ Blu Ray rips to both my TV frontends at the same time using NFS (which I will use) and everything worked great. I don't see me ever having a use more demanding that that, so the speed advantages of some forms of RAID don't help me.

5. (The Big Reason) It seems like a huge point of RAID (or JBOD or WHS or Unraid or Drobos) is to make it so that all your different hard disks act as a single drive. But the media frontend software I use (XBMC) allows me to add in a ton of different directories as sources, and then it scrapes those directories into a single library. Having all my media seem like they are on one disk is useless to me.

So what do you all think? Am I missing something big here? Or are you just shocked that I am considering building a server without RAID and I need to turn in my geek card?

Advice is very welcome.