DIY NAS/Home Server Questions

[Jesse B]

Recently I've delved into the world of NAS's and Homer Servers, and I seem to have caught the bug; I want one. They seem very convenient, and to put it simply, I have a lot of stuff, media mostly. However, not having ever dealt with most of the topics related to building one of these, I do have a few questions that need answering.

1.) Do I need a raid controller? My MoBo has 4 SATAII ports on board. I want to go with Hardware RAID, not Software RAID. Would I be able to run Hardware RAID off of the MoBo’s SATA ports, or do you need a dedicated RAID controller?

2.) Let’s assume I need a Raid Controller. My criteria for this piece of hardware have run me into some roadblocks. First off, I'm not rich, so I need this card to be as inexpensive as possible. Note how I said inexpensive, not cheap; I'm willing to pay a bit more as long as I feel it's absolutely necessary. It can require pretty much any expansion slot it needs, as there's quite a variety on my MoBo. It needs to have the ability to connect 4 SATAII drives (possibly less, refer to the next question), whether it be via SATAII or SAS Ports. Lastly, it has to support Linux/BSD.

3.) I’m unsure which level of RAID would best suit my application. I need redundancy, as one of the main reasons I’d like a setup like this is so that all my data is backed up, but speed is still of moderate importance as well; I don’t want transfers taking ages. I’ve done some research, and I’ve kind of narrowed it down to a few options that I feel will work.

Raid 1, 2 Drives: Redundancy, No Increase to Speed, Lowest Cost.
Raid 5, 3 Drives: Redundancy, Slight Speed Increase, Medium Cost.
Raid 10, 4 Drives: Redundancy, Increase in Speed, Highest Cost.

I feel that RAID 10 would be my best option, just due to the fact that it does both of the things I’d like to achieve. However, I’m not sure whether or not the speed increase for RAID 10 over RAID 1 is worth doubling the price, so some input on this topic would be appreciated. RAID 5 with 3 Drives seemed interesting to me as well, so I just threw it in there; not sure whether or not it’s appropriate.

That’s about it for now. I’m sure more will pop up with time.

Thanks,


- Jesse

 

[msl]

If you want hardware RAID then I think you will need a RAID controller card. Motherboard RAID is usually reliant on software and is not true hardware RAID.

However, why do you need hardware RAID? Software RAID works very nicely in Linux with any modern CPU, saves you money, and doesn't tie you in to a specific hardware RAID implementation. I think you are unlikely to see any significant performance difference between hardware and Linux software RAID in home usage.

I'm sure other people will be along soon if they have better information.

 

[msl]

It is worth pointing out that your RAID level comparisons are not like-for-like.

• Your RAID 1 (2 disk) configuration will give you 1 disk worth of storage.
• Your RAID 5 (3 disk) configuration will give you 2 disks worth of storage.
• Your RAID 10 (4 disk) configuration will give you 2 disks worth of storage.

RAID 10 is mirroring (i.e. RAID 1) for redundancy combined with striping (i.e. RAID 0) for performance. By default it uses one redundant copy so you get half the total disk space available for storage. You can create a RAID 10 array in Linux using any number of disks from two upwards, including odd numbers.

 

[Jesse B]

If you want hardware RAID then I think you will need a RAID controller card. Motherboard RAID is usually reliant on software and is not true hardware RAID.

Alright, figured as much. Thanks

However, why do you need hardware RAID? Software RAID works very nicely in Linux with any modern CPU, saves you money, and doesn't tie you in to a specific hardware RAID implementation. I think you are unlikely to see any significant performance difference between hardware and Linux software RAID in home usage.

I've heard from many gurus that software RAID should be avoided. I don't like the idea of my data being controlled by the OS, because if something goes wrong, then there's the potential for everything to go terribly awry. I feel more comfortable having a dedicated controller. If this information is incorrect please feel free to chime in, this is just what I have learned.

It is worth pointing out that your RAID level comparisons are not like-for-like.

I guess I forgot to explain my reasoning behind the 3 different RAID levels, so my mistake; I'll attempt to explain.

RAID 1, while having 1 disk worth of storage, would allow be to buy larger disks for an equal or lesser value, therefore allowing for the storage to be equivalent. However, I'm not sure how the performance is with the specific level of RAID.
RAID 5 would allow me to have redundant storage, while improving speeds slightly. I'm unsure what kind of speed increase this would result in, but I like the idea of increasing speed while still having redundancy.
RAID 1+0 would cost the most, having 4 disks. However, I'm aware that this setup yields and increase in speed along with the mirroring. If the increase in speed is worth the cost of a 4th drive, I'd be happy to go with this option.

I'm open to either of those 3. RAID1 is appealing, due to it's lowest cost, but I'm unsure of the performance. RAID5 (with 3 disks) seems to be the ideal setup (to myself, being a noob), as it gives my data complete security from loss, while increasing the speed. However, I have this gut feeling that RAID10 will have the greatest increase in performance. However, as I mentioned, I don't know enough about this topic to make accurate predictions.

Thanks for the replies,


- Jesse

 

[msl]

I think you might not have got the point I was making about the RAID configurations you are proposing. Your RAID 1 configuration is cheaper because you are only paying for half the storage space compared to the RAID 5 and 10 configurations. RAID 1 and RAID 10 cost the same.

 

[Jesse B]

I think you might not have got the point I was making about the RAID configurations you are proposing. Your RAID 1 configuration is cheaper because you are only paying for half the storage space compared to the RAID 5 and 10 configurations. RAID 1 and RAID 10 cost the same.

Ahh, gotcha. Sorry for the misunderstanding.

Really the only thing I'm wondering is how much of a performance increase I'd be looking at with 5/10 over 1 at this point in time.

 

[msl]

There are some performance figures and links for Linux software RAID here:

https://raid.wiki.kernel.org/index.php/Performance

 

[thiggins]

You didn't say how much storage that you are looking for. With 2TB and soon 3 TB drives, you can store a lot of stuff without RAID.

The main advantage a hardware RAID card gives you is the ability to move it and your drives to another host box. You can't easily move drives in software based NASes, except to another copy of the same box.

You're not really going to see a performance increase going from RAID 1 to 5. If anything, you'll see a decrease due to the higher computational load for 5.
Check the NAS charts to see differences between 5 and 10. (Pick a NAS, then use the Benchmarks button.) To my eye, there isn't a significant difference.

 

[Jesse B]

You didn't say how much storage that you are looking for. With 2TB and soon 3 TB drives, you can store a lot of stuff without RAID.

This is true, but the main reason I wanted to go with a RAID setup is so that my data would constantly be backed up. The thought of losing my data is quite worrying, so I just wanted something that gave me a bit of security.

You're not really going to see a performance increase going from RAID 1 to 5. If anything, you'll see a decrease due to the higher computational load for 5.
Check the NAS charts to see differences between 5 and 10. (Pick a NAS, then use the Benchmarks button.) To my eye, there isn't a significant difference.

Alright, thanks for the input. I'll do some thinking and consider my options.

 

[thiggins]

This is true, but the main reason I wanted to go with a RAID setup is so that my data would constantly be backed up. The thought of losing my data is quite worrying, so I just wanted something that gave me a bit of security.

RAID is not backup. It is a technique for making a larger storage volume out of multiple smaller capacity drives.

 

[Jesse B]

RAID is not backup. It is a technique for making a larger storage volume out of multiple smaller capacity drives.

I'm in no way trying to be rude, but I don't see how mirroring a drive isn't backup? Would you mind explaining this to me?

Thanks,


- Jesse

 

[bookmage]

What OS will be running on it? How powerful is the system and what will the system be doing? just file sharing? media encoding?

How you setup your drives depends on what they will be doing.

Unless you really need the performance and have the network to support it, RAID10 is usually overkill for a storage server and may or may not match your network speed. depending on your setup, RAID10 could be greater than your gig network which wouldn't be cost beneficial over a RAID5/RAID6. RAID10 is usually used for databases where internal data speeds are needed to process data.

I would opt for RAID5/6 depending on how many drives I go. Any real Hardware controller supports RAID6 and I would use RAID6 for anything over 8 drives. comparable performance to RAID5, but you can survive a 2 drive loss. I use software RAID, since HW RAID is depending on having hte same controller and same setup. If the RAID controller dies, you have to find the same one or a compatible one to recover your data. If the controller isn't around in 3+ years, you would have a hard time recovering data.
Using software RAID allows me to use any hardware that works in linux and I have more options with my RAID array. HW controllers use software to implement RAID similar to software RAID so you would be letting the OS on the controller card to manager your data. It's no different then running software RAID. The only difference is that HW controllers have its own cpu for processing read/writes and they have a nicer user interface for managing drives. Companies do use HW controllers so if something goes wrong, they have a company to contact to troubleshoot and restore data.

RAID isn't a backup. It's to prevent data loss from minor hardware failure usually losing a drive. But there are other things that can go wrong, such as multiple drives dying, user deletion, file corruption, etc. I've had 2 drives in a raid set suffer the same hardware failure after 2 years and lost the drive array. I have another drive array that I keep as a backup and didn't lose much data. But make sure you have a contingency plan in case you lose your data on that array.

 

[Jesse B]

Alright, thank you very much. I've been talking with some people that explained in layman's terms the advantages and disadvantages of both Hardware and Software RAID, and software is sounding a lot more appealing now.

What OS will be running on it? How powerful is the system and what will the system be doing? just file sharing? media encoding?

I'm just using the hardware out of a spare PC I'm not really using for anything. It's got a dual-core @ 2.9GHz, 2GB of DDR3, and then just embedded HD graphics.

Not 100% sure on the OS yet, but I'm leaning towards something like Ubuntu (as I'm quite familiar with this) or even maybe BSD. I'm not really wanting to run Windows on this.

This system will be primarily for file sharing, but I wouldn't mind if I could get it to stream to my PS3/Primary PC to play videos/music/etc. I'm not sure what would be required for this. I'll assume I'd need an add-on video card to stream HD video? I think the chipset is the HD4200 or something like that.

I would opt for RAID5/6 depending on how many drives I go.

I'm not planning on having very many drives, as they're still fairly expensive. I'm thinking of running RAID5 with 3 drives, either 1TB or 1.5TB each probably.

Thanks again for all the help,


- Jesse

 

[thiggins]

I'm in no way trying to be rude, but I don't see how mirroring a drive isn't backup? Would you mind explaining this to me?

No offense taken. Was bookmage's explanation of how RAID can fail sufficient?

 

[Jesse B]

No offense taken. Was bookmage's explanation of how RAID can fail sufficient?

Yep, I understand now. Mirroring just makes it seem like it's backed up; I assume that's a classic noob mistake

Thanks again for the help everybody,


- Jesse

 

[Jesse B]

Another quick question. This is what it says under Specs for the Motherboard I have:

RAID 0/1/0+1/JBOD

Will Software-RAID5 still work with this board?

 

[thiggins]

Assuming that the mobo is using an Intel chipset, no, RAID 5 won't work with the Intel RAID software.

 

[Jesse B]

It's actually an AMD chipset

Chipset AMD® 785G+SB710

Not sure if that makes a difference or not.

 

[msl]

Linux software RAID 5 should work fine. It doesn't rely on any RAID capabilities on the motherboard.

 

[thiggins]

Linux software RAID 5 should work fine. It doesn't rely on any RAID capabilities on the motherboard.

Oops, sorry!

msl is correct. I was thinking of just the ability for the mobo to put multiple drives into a RAID array for normal Windows use.