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What is the best raid level for HTPC?

post #1 of 64
Thread Starter 
I am starting to get a large movie collections, with now over 400 movies using 7TB's of data, at the moment i am currently using JBOD.

I want to start a RAID but not quite sure which is the most efficient.

I don't think i need anything over a 1 disk fault tolerance.

So is RAID 5 my best bet?
post #2 of 64
Flex Raid or UnRaid

Two similar, yet very different options.
Use the search feature. Then Google.
You will be reading for days...

I personally went Windows Home Server with FlexRaid. Works great.
post #3 of 64
RAID 5 would give you the best over all in efficiency, giving good use of available storage space (more drives in the array the the better for this as total storage is (smallest drive)x(number of drives-1) but more drives gives a higher chance of a second drive failure before rebuilding a failed drive) and better performance over JBOB or flexRAID (more drives in the array will higher read/write rates). If you're looking for performance use a true hardware RAID controller(one w/ a lot of ram will give you good write speeds), your onboard RAID is most likely a softRAID as is most of the cheaper controller cards

FlexRAID as stated above is also a good choice while not giving any added performance increase over JBOD it gives you a plus over RAID 5 that if you have multiple drive failures you only loose data on those drives while RAID 5 would lose the whole array (there is software that can recover data from stripped arrays but there's no guaranty that you'll be able to save all or any of you data).

UnRAID would be similar to flexRAID but used on a media server (I'm not sure if you're using one or just a HTPC w/ large storage).
post #4 of 64
I would like to disagree on hardware RAID controllers. On a modern processor parity calculations take up hardly any cpu in both Linux and Windows Server - something like 6GBps with 3% cpu.

A true hw controller is expensive ($300+) and you are tied to that controller family for recovering the array. For home use it just isn't worth it, esp on a media server which will see very few writes.

If you decide to use WHS, be aware it doesn't support newer drives (2TB and larger using 4k sectors) and is not being developed anymore.
post #5 of 64
Are we talking about HTPC?

No RAID is needed.
post #6 of 64
I'l also echo the comment about read/writes. Unless you're constantly editing files on the NAS there is no need for powerful raid card. Even if you are worried about write speeds you can use a Cache drive in an unRaid config.
post #7 of 64
Some external HDDs for movie storage... Just plug and play lots of movies.
post #8 of 64
Quote:
Originally Posted by Defcon View Post


If you decide to use WHS, be aware it doesn't support newer drives (2TB and larger using 4k sectors) and is not being developed anymore.

Ummmm....
I have three, 2tb drives.... All you need to do is add a little plastic/metal jumper and short 2 pins. simple. Performance is around 70-90mb's. Never had so much of as a hiccup setting WHS up with these drives.
LL
post #9 of 64
Thread Starter 
I am not concerned about speed, as long as the throughput can play my blu-rays that is all i need, the main reason for the raid is redundancy, not speed.
post #10 of 64
Quote:
Originally Posted by Defcon View Post

I would like to disagree on hardware RAID controllers. On a modern processor parity calculations take up hardly any cpu in both Linux and Windows Server - something like 6GBps with 3% cpu.

A true hw controller is expensive ($300+) and you are tied to that controller family for recovering the array. For home use it just isn't worth it, esp on a media server which will see very few writes.


Its not so much the calculations and throughput, in my opinion, as it is the dependability. You can pick up hardware raid controllers for a little over $100 (check Dell PERC5/i). With a battery backup, you won't lose data should your cmos battery die. Have you ever had a dead CMOS battery and have the power go out on a software/motherboard raid system? Guess what. Everything is GONE. Ask me how I know. Also, FWIW, you're tied to whatever you're using for recovering the array for any RAID, not just hardware RAID.


Quote:
Originally Posted by Defcon View Post

... WHS ... is not being developed anymore.

Umm... dude... there's a new beta out called Vail. It is 100% still being developed.
post #11 of 64
Quote:
Originally Posted by NeveSSL View Post

Its not so much the calculations and throughput, in my opinion, as it is the dependability. You can pick up hardware raid controllers for a little over $100 (check Dell PERC5/i).

Beware, don't expect a Dell card to just work, I bought a PERC6/i and it wasn't compatible with my Tyan motherboard, it would likely be less compatible with the HTPC motherboards than the Tyan motherboard which was a server board.

I would suggest software RAID unless you are having issues with CPU utilization. A software raid controller for raid 5/6 should be alright if you aren't concerned about CPU. Also software RAID is easier to recover than hardware RAID since software RAID is done in the OS(Window/Linux) and not in the hardware. If the hardware RAID controller dies you really need an exact match where in software you just need the same OS.

I went the more expensive route and picked up an Areca ARC-1680ix-24 along with a 24 bay hot-swappable chassis but I spent around $4k on this which will serve as permanent storage for every computer in my house for many, many years. Currently have 12tb of storage in a RAID 6 array with 300MBs performance.

Do as I say, not as I do I have spent around $10k on my home setup.
post #12 of 64
Quote:
Originally Posted by NeveSSL View Post

Its not so much the calculations and throughput, in my opinion, as it is the dependability. You can pick up hardware raid controllers for a little over $100 (check Dell PERC5/i). With a battery backup, you won't lose data should your cmos battery die. Have you ever had a dead CMOS battery and have the power go out on a software/motherboard raid system? Guess what. Everything is GONE. Ask me how I know. Also, FWIW, you're tied to whatever you're using for recovering the array for any RAID, not just hardware RAID.




Umm... dude... there's a new beta out called Vail. It is 100% still being developed.

I'm sure you've heard that DE is dropped from Vail. Without DE Vail is nothing special, this thread is about data redundancy and only WHS with its DE is unique in that regard. Vail has NO announced replacement for it.
post #13 of 64
Quote:
Originally Posted by ricabullah View Post

Are we talking about HTPC?

No RAID is needed.



With the time it takes to gather media, some kind of data protection is necessary in my opinion.

I have 8x2tb drives in an external enclosure running raid5. I'd run raid6 if I had a better controller.
post #14 of 64
Well, technically for a HTPC you don't need RAID. In the most basic sense a HTPC just plays media...if you start considering RAID it is typically suggested to build a standalone system to store the media...aka a media server.

ricabullah was just being funny.

You are in no way limited to this setup, though it is recommended to have a separate media server if you have multiple HTPCs accessing your media. If you only have one HTPC you can effectively combine the HTPC and media server into an all-in-one computer. In that case I would either go with hardware RAID or FlexRAID and since I use FlexRAID I think you know which solution I'd suggest...
post #15 of 64
Is anyone using Greyhole? Or maybe Amahi? I'm thinking it may be nice... I might have to try it.

Brandon
post #16 of 64
OK, you seem new to RAID. A RAID 5 or RAID 6 array will stripe the data across all disks. This means that each disk holds some of the data. There is also some redundant error checking data which can re-create the data lost if either 1 or 2 disks go missing. So, RAID5 or RAID6 allows you to recover from one or two failed disks. However, it also means complete loss of all data stored on the array when you go above these disk failure levels.

A RAID controller will generally flag a disk as failed if it doesn't respond properly within a certain time limit. Once it is flagged as failed it must be treated just like a disk that did actually fail. Enterprise drives are built with this in mind and will respond within a reasonable time limit. Cheap home drives are not and they may cause timeouts and disk failures to appear.

There are 3 general types of RAID systems. You can have an add-in RAID card, the operating system do the RAID or the motherboard and BIOS do the RAID. Generally, I've listed these in order from best to worst. In some cases, the add-in RAID card is a piece of crap. Windows doesn't do software RAID.

So, you have to decide. Do I place all my data into a system where either 2 drives or 3 drives fail and I've lost it all? Do I find an alternative that will at least leave me with data on my remaining good drives even if 2 or 3 drives fail?

I personally see no good reason for using a RAID5 or RAID6 array at home. I'm running an unRAID server and copy my important data to an external drive I keep off-site.

Good luck with your decision.

Peter
post #17 of 64
Another vote for a dedicated Unraid server. Having your data on your HTPC pretty much guarantees too many hot things in one small box where you can hear it...
post #18 of 64
Did you guys pay for the upgraded version of unRAID? Seems nice, but Grayhole on Amahi does the same thing for free.

Brandon
post #19 of 64
Greyhole is great if you are a Linux expert. Things like adding a disk to the pool still need a lot of arcane cmd line magic, its not really for the end user. I hope this will be fixed when its no longer beta.

Greyhole is also based on the 1st version of DE so it still uses a landing zone - i.e. the designated disk mus have enough space for the file copy, it does not copy files to a target disk. Its a bit like cache disk in unRaid.
post #20 of 64
Quote:
Originally Posted by NeveSSL View Post

Did you guys pay for the upgraded version of unRAID? Seems nice, but Grayhole on Amahi does the same thing for free.

Brandon


From the Amahi web site;

"Does Amahi support RAID?
Yes, you can use hardware RAID or software RAID with your Amahi server! "

There are all kinds of systems that give you that (figure it out yourself). So, Greyhole adds some kind of redundancy similar to WHS making duplicate data on different disks. But, have you read how to use Greyhole? Have you read the warnings? It runs at midnight? Relies on a SQL server? You write the file and then it is replaced by a link to the new file(s) Greyhole creates in your storage pool? Honestly, I start to read this and go WTF, can you make it any more difficult?

I mainly chose unRAID because of it's simplicity and the parity drive protection. A share is just the combination of like named top level directories on the disks. I can write to the share or to the directory on the disk interchangably. The parity provides live real-time protection against a failed disk. It's really all VERY simple and works VERY well.

The only other option besides unRAID for a parity was Flexraid with it's snapshot RAID. It wasn't very user friendly either at the time I purchased unRAID.

Peter
post #21 of 64
I've been using an unRAID server for almost four years now. Total capacity is approximately 20TB with fifteen drives in the array (14 data and one parity). I've had a couple of wonky drives in the array and was able to completely restore the data using the parity drive. The problem turned out to be a flaky SATA backplane that has since been replaced. The array is up 24/7 and I can stream Blu-Ray and DVD rips to any room in the house.

I like unRAID because it provides me with huge amounts of storage that can be shared throughout my household. The use of a parity drive has saved me from huge amounts of data loss over the years. You can start with a 3-drive setup with the free version and then work your way up to a larger array with the paid licenses.

The Pro version is the best deal and you can get a 2nd license for only $30 more. The Pro version sells for $119 and two keys are only $149. If you go in with someone and split the cost for two keys you can get a single Pro key for just $75. You can get an additional $10 off during Lime Technology's current sale that's going on.

If you don't have a USB drive then you can get them pre-configured and bootable. Strangely, the additional cost for a single drive and two drives is $20 more than the license fees. A 2-pack of bootable flash drives is $169.
post #22 of 64
I don't think RAID is consumer tech. There are way too many issues and restrictions. A lot of enthusiasts use RAID for other purposes like increased read speeds. IMO any technology that doesn't keep data in native format is not simple to use an potentially dangerous - this includes JBOD, RAID, new DE in Vail, Drobo.

What does a home user want?


- data should be accessible at all times without proprietary hw or sw
- data safety
- simplicity
- be able to mix and match drives without regard to size, type or performace characteristics
- drive consolidation into a single pool

Not coincidentally, these are the precise design goals of WHS and unRAID. unRaid does seem like the easiest and safest 'no hassle' solution out there, and its advantage over WHS is it uses parity rather than duplication for data safety so its more efficient.
post #23 of 64
Thread Starter 
I agree with those who say that our cheap 2tb home drives are not designed for an enterprise level. I think if someone is going to build a hardware raid, they need to use enterprise drives. So for HTPC's and media servers, users should stick with software RAID's.

Is there any open source that can compete with unRAID?
post #24 of 64
Quote:
Originally Posted by Defcon View Post

I don't think RAID is consumer tech. There are way too many issues and restrictions. A lot of enthusiasts use RAID for other purposes like increased read speeds. IMO any technology that doesn't keep data in native format is not simple to use an potentially dangerous - this includes JBOD, RAID, new DE in Vail, Drobo.

What does a home user want?


- data should be accessible at all times without proprietary hw or sw
- data safety
- simplicity
- be able to mix and match drives without regard to size, type or performace characteristics
- drive consolidation into a single pool

Not coincidentally, these are the precise design goals of WHS and unRAID. unRaid does seem like the easiest and safest 'no hassle' solution out there, and its advantage over WHS is it uses parity rather than duplication for data safety so its more efficient.

unRAID is a RAID. From reading their wiki it seems the free version is RAID 5. It may not be proprietary SW that is doing the RAID but it is RAID. So it has some of the limitations you list above, such as it will need to have 3 equally sized disks or it won't use the entire disk, e.g. if you have 2x1TB and 1x512GB it will use only 512GB from each of the 1TB drives.
post #25 of 64
Quote:
Originally Posted by krodami View Post

I agree with those who say that our cheap 2tb home drives are not designed for an enterprise level. I think if someone is going to build a hardware raid, they need to use enterprise drives. So for HTPC's and media servers, users should stick with software RAID's.

Is there any open source that can compete with unRAID?

I have 8xSeagate Barracuda LP ST32000542AS 2TB 5900 RPM 32MB and they work like a champ on an Areca ARC-1680ix-24 RAID controller. But this doesn't mean all drives will work, the WD drives are garbage and don't work well.

If you want a free NAS look into FreeNAS(FreeBSD based) and OpenFiler(Linux based). I am using OpenFiler to access my drives. You can setup SAMBA shares or expose them as iSCSI devices. Simple configuration(SAMBA) is pretty easy while the more advanced iSCSI is not so easy.
post #26 of 64
Quote:
Originally Posted by taylorjonl View Post

unRAID is a RAID. From reading their wiki it seems the free version is RAID 5. It may not be proprietary SW that is doing the RAID but it is RAID. So it has some of the limitations you list above, such as it will need to have 3 equally sized disks or it won't use the entire disk, e.g. if you have 2x1TB and 1x512GB it will use only 512GB from each of the 1TB drives.

unRAID is not RAID. It's basically JBOD with one drive dedicated to parity protection. The only limitation is the parity drive has to be of equal or greater size to the largest drive in the array. It's basically the same as having a whole bunch of NTFS formatted drives and creating .par files and storing all the .par files on another drive, except in unRAID's case, parity is calculated on the HDD sector level instead of file level.
post #27 of 64
Quote:
Originally Posted by ilovejedd View Post

unRAID is not RAID. It's basically JBOD with one drive dedicated to parity protection. The only limitation is the parity drive has to be of equal or greater size to the largest drive in the array. It's basically the same as having a whole bunch of NTFS formatted drives and creating .par files and storing all the .par files on another drive, except in unRAID's case, parity is calculated on the HDD sector level instead of file level.

I was wrong that it is RAID 5. Call it RAID or don't call it RAID, this is what wikipedia calls it.

Quote:


UnRAID

UnRAID is best compared with RAID 3/RAID 4, without striping. Data drives are kept in normal reiserfs format, but a 'smart' parity drive emulates the function that striping plays in RAID3 and RAID4 with a specialized data structure. Pointers on the parity drive combine files on the various drives into virtual stripes which then get parity data. Read checksum are checked against the parity checksum (and reconstructed if incorrect.) Writes create new parity information. The main advantages to this approach are: data drives are readable and writeable on any system, separated from their arraythe system can fail without harming the array; different-sized drives can be combined; partial recovery is possible if the number of failures exceeds the number of parity disks (usually one).

Based on distributed, unsupported[23] GPL source code, UnRAID is suited to cheap, simple, expandable archival storage, similar to the more extreme write-once, read occasionally use case.

Disadvantages include slower performance than any single disk in both read and write, slow drive rebuild, filesystem overhead (additional checksums are required to avoid querying the other disks to check the data disks in use), scaling problems, much larger IO burden on the parity drive than other drives, bottlenecking when multiple drives are used concurrently. The parity drive must be at least as large as the largest data drive to provide protection. UnRAID is implemented as an add-on to the Linux MD layer.[24]

Personally I prefer RAID 5 or 6 over the description above but if you had 3 disks that weren't the same size then I guess it could be an decent solution.
post #28 of 64
Wikipedia isn't always correct, as proven by that quoted info above...
post #29 of 64
Quote:
Originally Posted by JoshDorhyke View Post

Wikipedia isn't always correct, as proven by that quoted info above...

What is incorrect about Wikipedia in this situation?
post #30 of 64
Quote:
Originally Posted by taylorjonl View Post

unRAID is a RAID. From reading their wiki it seems the free version is RAID 5. It may not be proprietary SW that is doing the RAID but it is RAID. So it has some of the limitations you list above, such as it will need to have 3 equally sized disks or it won't use the entire disk, e.g. if you have 2x1TB and 1x512GB it will use only 512GB from each of the 1TB drives.

Not true (with regards to the disk sizes and utility). You have to use the largest available drive as the parity drive. In the three disk scenario you cited, you would use a 1TB drive for parity and the other 1TB drive and the 512GB drive for the data drives. The full capacities of both data drives is available for use.

The nice feature about unRAID is that you can mix and match capacities and types of drives (i.e., SATA and PATA) within the array. If you've got a few older drives sitting around not being used, then you can build an unRAID server from existing parts.
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