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mdadm vs. FlexRAID

post #1 of 28
Thread Starter 
Hello!

Before I being explaining, let me first say... I am NOT going with hardware RAID (cost), ZFS, WHS, or unRAID. I've explored the options, and those are not what I'm looking at.

Server Purpose: streaming 1:1 Bluray rips primarily. Serving up files twice a month at LANs. 5-10 Blurays a week are added to the server (~35GB each)

My drives:
2x 1.5TB Seagate LP
8x 1TB WD Black
5x 2TB Hitachi 5k3000
In 3-3x5 Hot Swap Backplanes in CM590 for a total of 15 drives.
9TB of unique data currently on the drives.

I plan on phasing out all 1's and 1.5's for the Hitachi 2's 2 or 3 at a time. After all is said and done I will probably have 14 2TB's, leaving a 1TB for OS and temp torrent storage.

My Conclusions:
mdadm RAID: Would go RAID5 across the 5 2TB's right off the bat. Expand the array 2 or 3 disks at a time and convert it to a RAID6 once 10 drives has been reached. Losing a disk is less likely than a configuration error or user mess up. Much faster than FlexRAID. If more drives is lost than allowed, ALL data is destroyed. I've realized that 3 disk failures is very improbable and more than likely would be a user fault if data is destroyed. I'm fairly familiar with Linux, but have never created a RAID with it.

FlexRAID: Would sit on top of Server 2k8 and use all my current drives. Would be very flexible to include 3TB+ drives as they come out. Limited to single drive speeds. Snapshot based parity (Until Live Parity is stable). If more drives are lost than allowed, data is only lost on the failed drives. Having Windows makes me comfortable. Existing data on disks can be just added.

Overall I think FlexRAID is more flexible and forgiving when it comes to data loss. It's much newer and not as proven. It's constantly being developed, and does have bugs. It's slower than MDADM, but can use drives of different size. FlexRAID sits on top of the file system and parities the data itself, not the drive.


I've lost TB's of data in the past to HW RAID, mainly a user error vs. hardware. I'm leaning toward FlexRAID, as I can keep all the data that is already on the disks (9TB of unique data), and I don't have to move anything or change to a different OS.

What would you guys do?
post #2 of 28
So if you're not using hardware raid, which mobo do you plan to use that's going to support 14 drives?
    
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post #3 of 28
Quote:
Originally Posted by Klue22;13137384 
So if you're not using hardware raid, which mobo do you plan to use that's going to support 14 drives?

There's more than just hardware RAID cards that offers high port counts.

An HBA such as those from LSI or Supermicro (or the 1300 series from Areca, but they're expensive & have issues so I wouldn't go there) offer high port counts at much lower cost than equivalent RAID cards - and can give much higher speeds also.

OP - I'm thinking of a FlexRAID parity base to my media server. I'm still a little nervous though as it does have issues (as you mentioned). I can't say I'm really that fond of the idea of leaving my data in the hands of any closed source software though (unRAID, FlexRAID, etc), but they are the best option for media storage (in my mind at least) because multiple drive failures only loses the data on the failed drives, not on the array. For larger media storage arrays where you can't justify full backups that's the only option in my book - I could stand to re-rip 2-4TB of a 20TB collection if I had to, but I'd hate to have a couple of failures mean I had to re-rip the whole lot...
post #4 of 28
Thread Starter 
Ahh my bad. I have 6 onboard, a 2 port PCI-e expansion card, and a Supermicro SASLP-MV8 8 port.
Quote:
Originally Posted by the_beast;13138005 
OP - I'm thinking of a FlexRAID parity base to my media server. I'm still a little nervous though as it does have issues (as you mentioned). I can't say I'm really that fond of the idea of leaving my data in the hands of any closed source software though (unRAID, FlexRAID, etc), but they are the best option for media storage (in my mind at least) because multiple drive failures only loses the data on the failed drives, not on the array. For larger media storage arrays where you can't justify full backups that's the only option in my book - I could stand to re-rip 2-4TB of a 20TB collection if I had to, but I'd hate to have a couple of failures mean I had to re-rip the whole lot...

That's how I'm thinking. If something goes wrong with mdadm RAID, I'd lose everything. Not to mention like RAID you have to have same-size disks, and can't use existing disks full of data. I'm leaning toward 2k8 w/ FlexRAID, I just wanted some opinions.
Edited by Bonz(TM) - 4/15/11 at 10:09am
post #5 of 28
I was under the impression 3 TB drives needed a special card or uefi BIOS to be recognised...? Or is that just to boot off one? Max pc was saying something about that...

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post #6 of 28
Thread Starter 
Quote:
Originally Posted by subassy;13138229 
I was under the impression 3 TB drives needed a special card or uefi BIOS to be recognised...? Or is that just to boot off one? Max pc was saying something about that...

Sent from my ADR6300 using Tapatalk

I'm pretty sure that's just to boot from.

I'm also pretty sure my SASLP-MV8 supports 3TB drives with the latest firmware. Not sure about the SiL3132 sata card I have. 2TB's are fine for now though.
post #7 of 28
Eh? Lots of confusion here.

If you lose a disk in a RAID5, you just replace it and wait a couple hours for the rebuild (while you keep watching your movie). This is no less true of mdraid.

If you lose a disk in a "FlexRAID" and the snapshot isn't up to date then you replace it, obtain a couple hundred Blu-Rays and copy them all back onto the new disk. Your day (or your whole weekend) is ruined.

I know exactly which one I would prefer. Windows makes me distinctly UNcomfortable; I can't imagine why anybody would trust it for something this important.
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post #8 of 28
Thread Starter 
Quote:
Originally Posted by error10;13139116 
Eh? Lots of confusion here.

If you lose a disk in a RAID5, you just replace it and wait a couple hours for the rebuild (while you keep watching your movie). This is no less true of mdraid.

If you lose a disk in a "FlexRAID" and the snapshot isn't up to date then you replace it, obtain a couple hundred Blu-Rays and copy them all back onto the new disk. Your day (or your whole weekend) is ruined.

I know exactly which one I would prefer. Windows makes me distinctly UNcomfortable; I can't imagine why anybody would trust it for something this important.

Exactly. I've ran hw RAID before, and I absolutely love it. I'm just looking at the best solution, and I mainly need somebody like you to argue the point of mdraid to me. I'm leaning more toward FlexRAID, and here is why.

- Windows to me, as probably 90% of the population, is very comfortable. Don't get me wrong, I'm fairly comfortable with Linux and have a few CentOS boxes myself.
- My data is fairly static. At MOST, 10 Blurays a week are added. Parity would be calculated probably on a weekly basis, so at MOST I would lose 10 BD's due to outdated parity. If 2 drives (or more than my # of parity drives) are lost, I would only lose the data on those drives. Granted, 4TB is a lot of data to lose... it's better than 20+.
- I want to grab ~2 2TB drives at a time rather than buy all of them right now. If a few months down the road, there is a good deal on 3TB drives, I can pick them up and use them in the FlexRAID with no problem. With mdraid I would have to create a new array (providing I have the space and # of disks) and then migrate data around. Just like any true RAID, there are limitations.

The only upside I'm seeing right now with mdraid (or RAID in general) is speed and availability. I can deal with ~50-90MB/s single drive speeds, and I can deal with a day's worth of downtime to rebuild a failed drive in FlexRAID.
post #9 of 28
Quote:
Originally Posted by Bonz™;13139255 
- Windows to me, as probably 90% of the population, is very comfortable. Don't get me wrong, I'm fairly comfortable with Linux and have a few CentOS boxes myself.

OK, well then I have a third option for you: Greyhole. This is what Drive Extender should have been.

If you use Amahi Home Server, then Greyhole is included. Not to mention various apps for streaming your video to your PS3, HDTV or whatever.
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post #10 of 28
Thread Starter 
Quote:
Originally Posted by error10;13139356 
OK, well then I have a third option for you: Greyhole. This is what Drive Extender should have been.

If you use Amahi Home Server, then Greyhole is included. Not to mention various apps for streaming your video to your PS3, HDTV or whatever.

I'm already running WHS, which solves my "storage pool" woes. I don't want to have to duplicate 10+ TB of Blurays. The whole RAID vs. md issue arose due to a space vs. redundancy issue when dealing with double digit TB's worth of HD content. I just don't have the money to duplicate such a fast growing collection. So right now I have all this HD content unprotected. I need to take care of it before it's too late.
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