Looking to Build Your Very First unRAID Server?

Don't know first hand but, looking at the manual It should be fine. When you install the 3TB drive(s), go into the BIOS and set the SATA mode to "AHCI". This will enable larger than 2.2TB drives in the BIOS. UnRAID 5 supports larger than 2.2TB drives so you will need to use one of the version 5 RC's. I'm using RC4 right now so I can use my 3TB drives in it.

BTW, nice board with 6 SATA connectors!

Hello Eskro and all,

This is a fantastic thread and I've been trying to take it all in like a sponge. One thing I haven't quite been able to get a clear answer on though. In all of the Eskro builds it is mentioned to upgrade RAM and CPU accordingly for plugins like SAB/CP/SB. Can anyone offer any recommendations of RAM/CPU as I am interested in setting up an unRAID and go all in with these plugins as well as potentially a MythTV backend.

I assume 4 Gb of RAM across 2 channels would be sufficient but is just any multi-core CPU adequate? Obv I am trying to get the most bang for my buck here. Thanks in advance.

Rob

I have the Sempron processor and am running Sab (Haven't installed and configured SB yet). I have 4GB ram in a single stick. Recommendations on the unRAID forums and some posts here are for a single channel for a small amount of power savings over a second stick.

I can tell you post processing by sab takes quite a while longer than on my desktop system but, for the lower power processor and not having my desktop tied up doing stuff it is well worth it.

Thanks for the response. So of course hardware will have an effect on the speed on unpacking/writing/etc.

I have also heard that there is some resistance out there to having a server perform both storage functions and applications (SAB/CP/SB). Granted you will lose a slot for a storage drive, but would there be a gain in performance if you installed say a SSD as a cache drive? I'm still a noob here so feel free to educate me.

Yes, you would have a gain in performance with a large SSD as a cache drive. There is no trim support in unRAID currently so users on the forums do report write performance degrading over time with some SSDs. SSDs with good idle garbage collection built into the firmware are recommended until trim support exists in unRAID. All SSD's have some level of garbage collection built into their firmware. The good ones do an idle garbage collection which will use the drive's idle time to do garbage collection tasks so there is no impact to performance.

Your SSD needs to be larger than the largest data transfer you may make to your server or else the transfer will fail. If you have a 64GB SSD and try to transfer 100GB of data to the unRAID server, it will fail.

I am currently using a 120GB SSD in mine, now that I have all of my stuff already backed up to the server so I don't have any expected, large transfers to make. Ultimately, since I currently have a 100Mbps network, the network is the bottleneck in write speeds so I don't really see any performance gain with the SSD versus a mechanical drive. I may put in a 3TB mechanical to give me plenty of transfer space and give me a drive I can use to hot swap in case one of my other drives ever fail.

So as a whole, if I want to build an unRAID server complete with plugins, I'd have an appropriately spec'ed CPU and RAM setup as well as a cache drive (mechanical or ssd) with a size larger than my largest possible write? I'd be losing a storage slot to a parity drive as well as cache. So two storage slots lost in all.

Mick, u mentioned that unRAID doesn't have support garbage collection on SSDs but does that issue exist if using a mechanical cache drive? I appreciate your advice here.

Oh boy, I'm not sure I fully understand the issues with garbage collection/trim on SSD's but I'll write it how I understand it. It may be correct or completely off base but I'm sure somebody smarter than me will confirm or deny this info. So with that, here we go...

SSD's can only write to an erased block. Since files on drives are really only deleted from the partition tables but the data remains in the physical location on the drive, those blocks aren't erased when you delete a file, on mechanical or SSDs.

Since an SSD can only write to an erased block, eventually, you will have used up all the blocks at some point of writing data to the drive. In order to write data to the drive after that, the SSD must find the block it is going to write data to, move the contents that isn't supposed to be deleted to the buffer, erase the block, rewrite the data that isn't supposed to be deleted back to the block and then write the new data to the erased portion, all of which takes time and causes a performance hit.

Garbage collection is a function in the firmware of SSD's that erases these blocks once the data is removed. Most will only do it once the drive detects all the blocks have been written to and the drive is idle. Some OS's have "trim" support which helps tell the SSD what blocks to erase and when to do it to help keep the drive performing well.

Mechanical drives can change a block on the fly regardless of what it's set to currently so they don't have performance problems as a result of writing to areas already written to or that aren't erased. So no, they don't have the risk of performance loss like the SSD's. However, keep in mind, many people are using SSD's for their cache drives with great success and there are recommended ones posted on the unRaid forums (as well as ones to stay away from).

That's how I understand it, some of this may even be accurate!!!!

I was just wondering about what "Shares" and "allocation method" setup people who mainly use unraid for xbmc use.

"User shares" seems to be the best for whats needed in relation to sharing but im unsure what to choose for Allcoation

Most-Free
In this method, the system will simply pick the disk which currently has the most free space

High-Water
In this method, the system will pick the disk which currently has the least free space that is still above a certain minimum (called the "high water" mark). Suppose in our example above, we have this situation

Split Level
Often media data will consolidated under a single directory, or directory tree. Then during playback the files will be accessed one after another. This is the case with the set of VOB files which make up a DVD movie. In this situation we want all the associated media files to be stored on the same physical disk if at all possible. This is because we don't want media playback to pause while the disk containing the next file spins up. unRAID OS solves this problem by introducing a configurable allocation parameter called "Split level".

Split Level: This is what im considering. I dont have all that many VOB files but I do have a few films that are split in to eg Aliens CD1, Aliens CD2.Would this be better for the smoothest playback. Does this means that if the movie is playing, the thumbnails and media will be on the same disc thus leaving other drives spin down?. Is this train of thought correct?

Like this perhaps?


Thanks guys

Also this is my first unraid build and installation so a good tip or what helped you the most starting would be appreciated
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(2012-06-21 19:25)Mick1152 Wrote:  Don't know first hand but, looking at the manual It should be fine. When you install the 3TB drive(s), go into the BIOS and set the SATA mode to "AHCI". This will enable larger than 2.2TB drives in the BIOS. UnRAID 5 supports larger than 2.2TB drives so you will need to use one of the version 5 RC's. I'm using RC4 right now so I can use my 3TB drives in it.

BTW, nice board with 6 SATA connectors!

Can anyone confirm that this solution worked for 3 TB drives? I am about to buy the same exact MB for my unRAID server and want to make sure that this will work. Thanks in advance!

(2012-07-01 21:25)ekirred Wrote:  

(2012-06-21 19:25)Mick1152 Wrote:  Don't know first hand but, looking at the manual It should be fine. When you install the 3TB drive(s), go into the BIOS and set the SATA mode to "AHCI". This will enable larger than 2.2TB drives in the BIOS. UnRAID 5 supports larger than 2.2TB drives so you will need to use one of the version 5 RC's. I'm using RC4 right now so I can use my 3TB drives in it.

BTW, nice board with 6 SATA connectors!

Can anyone confirm that this solution worked for 3 TB drives? I am about to buy the same exact MB for my unRAID server and want to make sure that this will work. Thanks in advance!

It's running fine with mine. Latest RC build.