RAID5+HS or RAID6 for Media Storage?

[michaeld]

Hello everyone,

I am finally going the media server route and will be ripping my 500+ BR and DVD collection. I already have a PC I use as my NAS (Win7/3.2GHz Xeon/16GB RAM/1GB hard wired LAN) and will be adding an 8-bay SAS/SATA enclosure and HW RAID card to it specifically for my movies and music.

What I'm not sure of is what RAID level to use. I've traditionally been a RAID5 guy, but I'm looking at 20-24TB of storage here.

RAID5 + a hot spare is one way to go. RAID6 would be the other way to go. Max data protection is the goal here. I have a good grasp on RAID levels and I'm sort of at the point of "Paralysis by Analysis."

I'm looking at streaming two HD streams, MAX from this array. Most likely it'll be just one stream, so blazing read performance isn't a requirement here.

I'd appreciate your thoughts on this as the RAID level will likely influence which drives (4TB vs. 6TB) drives I buy.

Thanks for your time.

 

[TuxDude]

RAID-6. The only downside of going to raid-6 is the higher random-write penalty, and you aren't going to be doing many random writes on a media server. On the upside is better read performance, and far more importantly, you still have some redundancy even after a drive fails - so that when you encounter a read-error while rebuilding after a drive failure the rebuild can still recover that sector and continue rebuilding the rest of the array. Getting a read error while recovering a raid-5 sucks, as it often means the entire rebuild job fails and then all data is lost.

But for media storage, you might want to look at not doing traditional RAID at all, and use something like snapraid instead. Snapraid with dual-parity would be my recommendation for your media storage.

 

[michaeld]

Thanks, TuxDude. I appreciate the detailed reply.

I am not familiar with Snapraid, so not sure if it runs on its' own Linux/Unix-based OS like FreeNAS does. I probably should have put in my original post that this direct attached storage must run on a Windows OS. I don't know much about Linux/Unix and I already have a NAS that I use for personal files/pictures. The NAS is beefy, hardware-wise and can easily handle the additional workload of media streaming, especially with another HW RAID card doing the heavy lifting.

RAID-6. The only downside of going to raid-6 is the higher random-write penalty, and you aren't going to be doing many random writes on a media server. On the upside is better read performance, and far more importantly, you still have some redundancy even after a drive fails - so that when you encounter a read-error while rebuilding after a drive failure the rebuild can still recover that sector and continue rebuilding the rest of the array. Getting a read error while recovering a raid-5 sucks, as it often means the entire rebuild job fails and then all data is lost.

But for media storage, you might want to look at not doing traditional RAID at all, and use something like snapraid instead. Snapraid with dual-parity would be my recommendation for your media storage.

 

[j_h_o]

I'm not sure I see the need for RAID6 if you're ripping discs. If there's a failure, you could re-rip.

I have some 3ware 9750 RAID5 arrays for this same purpose, which I cap at 5 disk members. All HGST. I get reasonable performance, some safety, and I keep the arrays small to mitigate risk.

Backup to another array if you want some insurance against failure; RAID6 doesn't really protect against accidental file deletion, etc.

I backup important RAID5 arrays using Bvckup2 to another JBOD on a separate server entirely. This hasn't happened much, but if a RAID5 array flakes, since I'm using cheap desktop drives, I start with fresh disks, and take the opportunity to upgrade to larger disks.

 

[Chuckleb]

Random thoughts so feel free to use accordingly

6TB HD NAS drives run cool and quiet. I have a set of 6 in a ZFS Z2 (aka RAID6-ish) configuration and have about 22TB available space with 2 parity drives. I threw in a 7th drive has a hotspare. We do this at work as well and usually do arrays of 12 drives (9 data, 2 parity, 1 HS).

I also use an 8TB Seagate Archive drive to rsync (robocopy) the data off to. This gives me cheap backups and you'd only need 3 to protect the ~22TBish of data. Since you're not randomly overwriting, you won't get hit with any sort of SHM penalty and the read rates are nice for recovery.

 

[archangel.dmitry]

If it is the only storage, you should get RAID6 at least.

 

[michaeld]

Thanks everyone for the replies! I love this place.

True; I could "just re-rip" in the event of a failed array. But, being as my spare time is basically a few hours per week (Job + Family = Have to schedule when I can do stuff), my spare time is really valuable to me. I only want to rip my discs once. And the discs will not be ripped directly to the DAS. I will rip them on my desktop, then transfer the ripped files to the DAS. This DAS will truly be a read-only repository of static data, not an active "NAS" in the common usage of the term.

RAID is not backup; this is something I'm very familiar with. I plan on purchasing a couple of large HDs, throwing them in the cheapest external USB3.0 enclosures I can find and that will be my backup solution. If I have to be selective about what I back up, so be it. For example: I am a big fan of 1970s/1980s Chinese Karate movies. You know..."Tiger Fist Death Blade Man From Canton vs. Eagle Claw Woman" really cheap movies. I have probably 50 of those movies...but they are not mandatory to back up for me. Lord of The Rings Box Set...that's a mandatory backup.

With this DAS array, I want to ensure the data is as well-protected as possible, WHILE running said DAS on a Windows box (Win7 to be exact). So, RAID6 it is. I really dislike losing 2 out of 8 drives to parity, but if I have to replace a drive now and then but never lose the main array or any data, it is worth it to me.

I have done the 24-drive rackmount thing....back when 1TB drives were the cost of a used car. I did away with my rackmount gear. Too big, too loud and too damn big. Going with an 8-bay DAS enclosure this time around (SANS Digital TR8X).

Thanks, everyone.

 

[Chuckleb]

I had actually just emailed you this but figured to post for others as well. I have one of those iSTAR 3x3.5" in 2x5.25" converter bays in the front of my server. This is where I shove the 8T archive drives. I can sync to the drives, eject them, and offline them. This reduces wear on the drives and I can also toss them in the safety deposit box. I do that for my core data (documents, scans, kids pics, etc..). An additional advantage of this route is that these bays are usually cooled with a fan unlike most USB enclosures so helps with heat issues.

 

[michaeld]

Thanks, Chuck. I had not thought of that. And off-site backup is a very smart thing to do. I guess I have to finally rent a safe deposit box at the bank vs. handing my friend an ext HD and telling him "Put this someplace safe."

 

[Patriot]

I didn't backup my rips because they were just rips.... then I had a dual drive failure on my R5 courtesy of seagate 3tb drives.
R6 + backup gets my vote.

 

[Chuckleb]

Another simple backup strategy, if you had ports. Just build a Spanned array on 3x8TB drives and set that up as a Crashplan target and set up crashplan to dump to those. Then you wouldn't have to remember to sync drives as it would only back up changed data as well as it does a verify of the backups every so often. If a drive out of the pool fails, replace and recreate the backup.

 

[michaeld]

I actually do have 4 ports available on the LSI9650 that runs the drives for my NAS (home file storage only) . I could put the backup target drives on that controller. That would really be a good backup as the DAS drives and backup drives would be on separate HW RAID controllers. I want the backup automated. Great idea, Chuck. Thanks.

FWIW, I went with 8 x 4TB HGST NAS drives. 2 of the drives will be lost to parity (RAID6) so I will have 24TB of space before formatting. Probably wind up with about 22.5TB or so (NTFS)

I would've liked a bit more space, but the 8 4TB drives put a big enough hole in my pocket. I currently have about 120 BRs and 400-ish DVDs. I should be able to fit all that on 22TB, but after ripping all the BRs, I'll rip a few DVDs to see how much space each rip takes, I'll decide whether I'm going to attempt to rip the entire collection or be semi-picky about what I rip.