I've been watching the lime-tech site in hopes of them having more rb-1200s in stock, but it doesn't appear that there are any coming soon.  Therefore, I've been thinking of buying the parts and building, but that leaves me with a couple questions about scalability and whether I can add stuff as I go.  I know that I will need most of it right away (since there is only 1 of most pieces) however, I think I will only need around 5 or 6 HDD initially (ultimately will prob need around . 

 

So my questions are:

1) As long as I need 9 or less drives, I do not need the drive cages and can save some $$$ there; however, if sometime down the road I need a 10th drive, can I add the cages to make room without it messing up the unraid configuration?

2) The PCI disk controllers, I will need 1 initially to get enough connections for the 5 drives, but can I add a 2nd one later should i need to go to the 9th drive without messing up the unraid config?

 

Basically, I know how to handle the hardware, but I'm not sure if making these alterations will mess up the lime-tech software part of the environment, I'd love to just get what I need now and scale as needed.

 

Thanks for taking the time to respond.

Do not use PCI SATA controllers unless you're informed about their performance impact.

 

Read these threads:

http://lime-technology.com/forum/index.php?topic=7520

http://lime-technology.com/forum/index.php?topic=7526.0

I was planning on following the hardware listed for the rb-1200 as closely as possible, which would then include the use of at least 1 Promise SATA300 TX4 PCI disk controller.  I understand that they would not be as responsive as the motherboard controller, but the Asus P5LD2-VM motherboard only has 4 sata connections as far as I can tell - so from the 5th drive on, I have no real choice but to do an expansion card.

 

 

I'm a big fan of emulating what Tom has used in the servers he has sold, but you have to understand the history of the RB-1200. It was introduced a really low price to clean out some parts Tom had and is not an optimal design.

 

In the early days of Unraid all disks were on the PCI bus. The bandwidth of the PCI bus is about 125M/sec, during parity checks that bandwidth had to be shared across all drives. Parity checks and drive rebuilds in the early days of 500GB and smaller drives were fairly quick. Now with multiple 2T. drives, it would take days. During parity checks the server is less responsive, but it is mostly a data integrity issue. When replacing a failed drive, you want the process to finish as quickly as possible, in case of another drive failure. By moving all drives to the PCIe bus, the parity check can be done in about 8 hours for 2T. drives. The process is also largely independent of number of drives in the array.

 

To save money I suggest following the "Recommended Builds" in the Wiki

 

http://lime-technology.com/wiki/index.php?title=Hardware_Compatibility

 

I would suggest using the Cooler Master 4-in-3 hard drive cage. Your drives will be cooler and you will save quite a bit of money. The Cooler Master 590 comes with one cage and adding two more will allow you to have twelve drives. Most motherboards you might choose will have 4-6 SATA ports. A PCIe expansion card can be used for the rest. Picking the right power supply and motherboard is the key.

Sounds reasonable, I will review those builds and see how things shake out.  Thanks.

I agree with the others.  The Budget Box specifically was designed after the RB-1200, but without using the PCI bus at all.  The final cost is similar to the RB-1200 as well, though you will have to buy the unRAID license separately, so I suppose it comes out about $100 more.

OK, so having reviewed the previous posts and links presented, here's my modified plan.  Please let me know if this will work without causing any issues with unRaid.

 

Phase 1:  Get started with minimum config of recommended system (adjusted mb based on other posts).  This will get me everything I need to start and hold most of my data.

1x AMD Sempron 140 Sargas 2.7GHz 1MB L2 Cache Socket AM3 45W Single-Core Processor SDX140HBGQBOX

1x ASUS M4A785T-M/CSM AM3 AMD 785G HDMI Micro ATX AMD Motherboard

1x Kingston 2GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Desktop Memory Model KVR800D2/2GR

1x CORSAIR Builder Series CX430 CMPSU-430CX 430W ATX12V Active PFC Power Supply

1x COOLER MASTER Centurion 590 RC-590-KKN1-GP Black SECC / ABS ATX Mid Tower Computer Case

3x Seagate Barracuda LP ST32000542AS 2TB 5900 RPM 32MB Cache SATA 3.0Gb/s 3.5" Hard Drive -Bare Drive

1x unRAID Server Pro USB Flash

 

Phase 2:  As needed, pick up extra hdd until I can hold all data with some room to spare

3x Seagate Barracuda LP ST32000542AS 2TB 5900 RPM 32MB Cache SATA 3.0Gb/s 3.5" Hard Drive -Bare Drive

 

Phase 3: Growth.  At this point the mb sata ports are full, so when needed, get the following:

3x SNT-3141 SATA-II Hot-Swap 4 Drive Enclosure

1x Supermicro Add-on Card AOC-SASLP-MV8 - Storage controller - 8 Channel - SATA-300 / SAS - 300 MBps - PCI Express x4

2x 3ware Serial Attached SCSI (SAS) Internal Cable - CBL-SFF8087OCF-05M

(1 at a time as needed) Seagate Barracuda LP ST32000542AS 2TB 5900 RPM 32MB Cache SATA 3.0Gb/s 3.5" Hard Drive -Bare Drive

 

I think this will get me the earliest start possible, while spreading the cost over time and preventing unneeded expense.  My main concerns are whether there will be any problems with the array later when I add the cages (forcing me to remount the existing hdds) and the expansion card (although I presume it will not be an issue as long as the physical data connections remain the same).  I was also wondering (based on the mb) if it is wiser to get 2x 1gb sticks of memory rather than 1x 2gb stick?

 

Thanks for all the help here.

 

3x Seagate Barracuda LP ST32000542AS 2TB 5900 RPM 32MB Cache SATA 3.0Gb/s 3.5" Hard Drive -Bare Drive

 

I was also wondering (based on the mb) if it is wiser to get 2x 1gb sticks of memory rather than 1x 2gb stick?

 

Just be sure to check into firmware updates for the Seagate drives.

 

I would just go with 1x 2gb stick. 

 

Everything looks fine, though I would also recommend a single 2 GB stick of RAM.  Same price, more expandability options later.

 

Also, don't buy 3 of the same hard drive at once, it increases your chances of a simultaneous multi-drive failure, something that unRAID can't fix.  Instead, either space out your purchases by a week or two, or buy three different drives (WD Green, Samsung EcoGreen, and Seagate LP for example).  Or if you insist on having all of the same make and model of drive, then buy each one from a different vendor (Newegg, TigerDirect, and Amazon, for example).

I was brought up in the old days of raid when identical drives were required.  In theory, I have no problem with mixing them up, but don't normally think that way (though I agree with using different vendors to get drives from different batches).  I guess at this time, the real question I'm faced with is whether buying the same drive from different vendors or buying different model drives really has much impact on preventing hardware failure.  At this point in my career, I've bought 100s of hard drives, and have never had one that arrived dead.  I've also only had one or two hard drives fail, and they were close to a decade old at the time.

I don't think it matters, either way will achieve the same results.  Just go with whichever is cheaper (taking shipping and tax into account).

 

It also took me a while to get used to the idea that identical drives and even wearing of drives is not a good thing.

I'll chime in with different opinion on the single/dual channel RAM.  I would recommend going dual channel (2x1).  In its most basic state, unRAID may not benefit much from the dual channel speed increase, but you may run into a situation later where you would gain from dual channel.  In my case, I have 4 GB of RAM and I have my unRAID setup to use 1.5 GB of this as cache for file transfers.  So the first 1.5 GB of transfer that I perform goes straight to RAM instead of the HDD, and then from the RAM to my unRAID HDD once the cache is full or 30 seconds has past.

 

The end result is that I get higher speeds on the first 1.5 GB of transfer (45-50 MB/s) and then speeds drop down to 30-35 MB/s after that.  With dual channel, your RAM has more bandwidth and may perform slightly better than single channel.  This will come into play more once you start adding plug-ins to unRAID, and still take advantage of the RAM cache.

 

Which dual channel is probably more important the more RAM you add.  At 2 GB, you may not have as much RAM to balance between cache, file system, and programs.  So it will be a trade-off between future expandability or immediate minor performance gain.

 

I also can't recommend the Icy Dock bays enough.  They are awesome!  Also, make sure to check out Icy Dock's website, so far this summer they have been running a rebate form on their SATA (not SAS though) bays.  You can buy one 5-n-3 each month an get $15 back.  My observation is that you will get much better cooling out of these than just sticking them in the stock case (maybe if you are adding extra fans to the case, you can match the cooling performance).

 

I would also advise against the ST32000542AS Seagate drives.  First, they have a known firmware problem.  I believe it has been fixed and new batches don't have a problem, but you never know the manufacture date when you order a drive online.  If you do get older drives with bad firmware, you can remedy the problem, but it is more work on your part.  Another reason I don't recommend the Seagates is because of their own stats, Unrecoverable read errors  1 in 10^14.  The Samsung and WD green drives are rated 1 in 10^15.  That is an order of magnitude higher before you lose a piece of data on the drive due to a read error.  They are also only rated for 50,000 load/unload cycles, vs. 300,000 cycles on WD and Samsung drives.  So on paper, the other drives should last longer, all things equal (ie no bearing failures, spindle shaft failures, controller failures, etc.).

^^ So I guess you don't use a cache drive as this is much faster? How did you set this up?

^^ So I guess you don't use a cache drive as this is much faster? How did you set this up?

 

Well, cache drive is MUCH bigger.  And you get the same speed boost when writing to the cache drive too.  And a cache drive dump can occur much later (it's going to happen in 30 seconds from RAM).   By default every unRAID sets aside some RAM and uses it in this way.  I think the default is 10%.  I believe this default is picked around a budget build that may only have 1GB of RAM.  The system can't spare more than 100 MB for a RAM cache (memory allotted this was can't be used for anything else, so assign too much and your system crashes).  However, if you system runs fine with 1 GB of RAM, setting aside 10% for a RAM cache, then it means you system only needs 900MB of RAM.  So if you then upgrade to 4GB or RAM, you still only need 900 MB, and can assign the extra RAM to increase your RAM cache.

 

The parameter is vm.dirty_ratio.  You can add it to your go file and set it to whatever you want.  I use

 

vm.dirty_ratio = 37 to get ~1.5 GB.  They guys on here who pointed out the setting to me use numbers like 70-80, but also change other parameters to avoid running out of memory (or they run more than 4 GB of RAM).

 

So when I copy a 1 GB episode of Big Bang Theory to my unRAID, it all goes into RAM at 45-50 MB/s.  30 seconds later, the OS writes it to the HDD while I'm off doing something else.  Overall, it will boost your average transfer speed on about anything.  I have noticed  that when transferring many small, highly fragmented files, you don't really gain anything because the originating drive is too slow finding all the files to sustain the faster rates.

 

 

Few review sites look into the performance impact of Single vs Dual vs Triple channel memory on current CPUS. I can't find the one review I saw recently, but it was generally the same results as the one I could find at TH's.

 

Tom's Hardware examined the Intel Core i7 CPU, which is the higher end of the community favored Intel Core i3 CPU (less performance but significantly less power consumption). The i3 has half of i7's L3 cache, only 4 MB, so the impact is likely to be slightly higher.

 

Toms Hardware:

Analysis: Triple-Channel vs. Dual-Channel and Single-Channel

 

We ran the entire benchmark suite once with each of the memory configurations. Our conclusion? It doesn’t matter much to the Core i7, with its 1 MB L2 cache and 8 MB L3 cache, whether it is running its memory in a triple-, dual-, or single-channel configuration. In everyday tasks, there is absolutely no tangible performance difference: the performance delta between a tri-channel and a single-channel configuration is only 2% on average. If you already own a dual-channel DDR3 memory kit and are planning to switch to the Core i7, you don’t need to spend the extra money on a third module to run your system in tri-channel mode.

 

As for the Seagate drives, they do have firmware issues to contend with. There's some hoops you need to jump through. Their firmware updater hasn't been updated to detect newer drives. This means you're left with having to force the firmware update by issuing the dos commands manually. You may also need to change your bios SATA settings to IDE for the purpose of the firmware update. After that, you'll want to change it back to AHCI. Because of these massive firmware issues, they earned the name 'Failgate' drives. I hadn't touched them for over 1.5 years because of those issues, and down the road I hope I don't regret picking up that 2TB Failgate drive a month ago.

 

In the same fashion, despite having several WD EADS drives, I'm very hesitant to pick up a WD EARS drive or even a WD EADS that has the Advanced Format.