Tell me about RAID 5

[five.five-six]

So, I sold a 6 drive RAID5... but building it is a bit more than I bargained for. I wanted to put the drives in an 2U enclosure but cost is becoming an issue. The server is in a 4U case with 3 available drive bays, 2 of which are 3.5" and 1 is 2.5" I will be combining the existing 3 drives with 3 new drives. can I use different drives as in some 2.5" and some 3.5"? My hardware budget for the 3 new drives and RAID controller is $900. It's a windows7 pro box with SP1, and I am looking at an Intel RT3WB080

[brianinca]

RAID5 is worthless for fault tolerance. Modern drives are too big to resynchronize quickly enough to be safe and reliable. If you have to have a parity RAID array, use RAID6. In general, you're better off going for non-parity RAID10, it is 50% overhead but the I/O and read/write performance is additive and your recovery time from a failed drive is MUCH shorter and won't risk your whole array.

Since you're buying a cheapie controller, parity RAID is a terrible idea regardless of any other factor. Any decent performance from RAID6 is going to mean ~$1K for the controller by itself.

How will you be backing up a storage volume that large?

Edit to add: I'd look at the 4x1 3.5" and 6x1 3.5" drive cages for 2.5" drives, you'll get best performance out of more smaller drives in RAID10 and that's a good way to get the drive count up.
Regards,
Brian in CA

[five.five-six]

Tell me about RAID 5

Recovery time isn't a factor, its for an NVR. capacity and fault tolerance are critical. The question i am really after is: should they all be the Same drive or is same size drive fine?


My real concern with RAID5 is write speed, im going to be sending it about 40mbps.


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[Mute]

Given your needs, and the number of drives you have available, you should do as brianca suggested and go with a RAID 10 setup.

[five.five-six]

Given your needs, and the number of drives you have available, you should do as brianca suggested and go with a RAID 10 setup.

Ok, in. RAID 10, can i use (4) 2TB drives and (2) 4TB drives?



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[ke6guj]

Ok, in. RAID 10, can i use (4) 2TB drives and (2) 4TB drives?



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could depend on your controller, but yes, you can do that.

You'd effectively have a 6TB drive. you would have (2+2+4) in a RAID0, but it would only use the first 2 on the 4TB drive, so you have 6TB. Then, that it mirrored on to the second pair.

you need to confirm that your controller will even support a 4TB drive. not all do.

[five.five-six]

you need to confirm that your controller will even support a 4TB drive. not all do.

Good point!

[five.five-six]

you need to confirm that your controller will even support a 4TB drive. not all do.

I just read the entire manual for the Intel RT3WB080 and it makes no mention of a drive size limitation. that's the beauty of newegg, they are like Home Depot, you can return anything

[ldsnet]

RAID uses a lot of overhead. The better systems (controllers) can handle different hard drives effectively, but unknown about your specific controller.

General rule is all the drives need to be the same size - makes it easer and faster for the controller. Which is more important to you? Your data, your budget or speed/reliability? You can only have TWO!!!

It sounds like you need to rethink your save priorities for your data.
The last RAID system I worked on was for a multi-user database system, where data loss was not acceptable, but access speed was not a concern, data protection was.

Most video files are a short view item (saved, watched a few times and ignored). If this is the case, traditional hard drives and a robust backup system may be more effective use of your budget.

[five.five-six]

I installed it yesterday, took about 2 hours including HW installation and setup. With BGI enabled I had available storage almost instantly. It is really fast for my needs. I am short 4 of the bigger cameras currently but the system is writing about 300GB a day.

Is there a way in 7 ultimate to have email alerts sent if there is a HW fault?

[the86d]

Kernel Raid5 on Linux boxes works well, no special controller needed, and the drive can be place into another box without issues.

I can't trust hardware controllers, as I have heard horror stories of the next model (the only one available after the old one dies) possibly not being able to read the older model's RAID, same with DROBO's...

[five.five-six]

Kernel Raid5 on Linux boxes works well, no special controller needed, and the drive can be place into another box without issues.

Unfortunately the CMS/VMS/NVR I use is not supported on Linux boxes.

[vikingm03]

What are "CMS/VMS/NVR" ? Anyways, I don't know if it would be available for you to use, but ZFS is a great filesystem that has built-in RAID#. It also has the capability to repair data that has been corrupted on the disk, which a lot of hardware RAID controllers don't do AFAIK.

[five.five-six]

CMS/VMS/NVR are generic terms for surveillance video management products.

[ocabj]

We use ZFS only because of our Sun/Solaris/Oracle hardware (we have a lot of it). It works, but I don't see it offering much cost (time/effort) to benefit ratio if you were to go OpenZFS or some other ZFS port.