RAID 5 Reliability - Any Nightmare Experience?

Why use true RAID at all? I've been running unRAID for years and am pretty happy. It's perfect for storing videos and whatnot but not something I'd use for say a high volume SQL database. Parity is stored on a single drive, each data drive is standard ReisferFS. If a drive fails standard tools could be used to recover it. If a single drive fails you swap in a new one and rebuild - you have access to the data while this occurs. IF God forbid two drives fail then you lose the data on those two drives and nothing else - you can try to recover them with ReiserFS tools. Since parity isn't striped only those disks being accessed are spun up. OS boots from a thumbdrive so no space is consumed by the OS. You can also use drives of varying brand\size\speed with no issue. The only rule is that parity be as big or bigger than the other drives. 3x 2TB drives would be 4TB of storage. 10x 2TB drives would be 18TB of storage. Make sense?

I run two of these servers currently. One of them has had as many as 15 drives in it in the past. Currently I've consolidated it down with 1.5TB drives and moved it from IDE to SATA (yeah, I've been doing this awhile!). This server has 12 drives in it currently but two are empty last I looked. My other machine has 10 drives and it's a catch all for drives. I used to have 750 all the way up to 2TB drives in it but have been slowly upgrading them all to 2TB drives and moving the old ones to the other server. I've yet to suffer a dual drive failure but I've had single drive failures about 4 times, none of them were traumatic and no data was lost. 3TB drives are now supported in beta software but when I tried upgrading to that software I ran into issues, starting one from scratch with the new stuff would likely be just fine.

Anyway, just a thought. Flex is another choice but I don't know as much about it. For home video serving full on RAID just doesn't make sense to me from an energy\heat\noise and cost aspect. <shrug>

P.S. green drives, slow drives, fast drives - all living together in my systems. I buy what's on sale when I need them!

I used RAID 5 for a few years to keep things cheap. The only nightmare was rebuilding, it can take days. It did recover successful... I just caved and bought another drive and use a RAID10 now, hard not too when the prices were so cheap last year.

Raid10? That's 2 raid 0 arrays in a mirror. You get 1/2 the bought capacity, ie 6 2TB drive = 6TB of usable capacity. That's seems to be a waste of HDDs when something like unraid/flexraid/etc gives everything you need for media storage and doesn't waste so many drives.

What about the Seagate Barracuda 3TB (ST3000DM001) to use in my NAS? I have a Synology 1512+ and it is on their list of supported drives. Would you guys recommend this for a RAID setup?

The first time I lost my array I ditched RAID 5 forever. It is fine for business use, but for a media server it adds risk (in the form of striping) to get speed you will never need.

I've used raid 5 arrays in business environments for many years. It's a good technology. It isn't totally safe though, and hardware failures can destroy an array. IE I've seen an array run for years 24*7*365. Then have a HDD failure. Power down, swap out the drive, power up and another drive is dead (translation, the entire array is dead, time for a restore).

You don't need a backup if the data is unimportant (IE your episodes of Sex in The City ).

Can't remember the link now but someone did a (software?) RAID6 with XFS and SSD type R/W's and put it through some serious stress testing as well. Some actual real numbers you can't get easily. Now, any kind of device like that has to absolutely go through something like a voltage regulator or a UPS so the line voltage fluctuations don't stress the electronics too much over the years and lead to more errors.

http://www.google.ca/webhp?hl=en&tab=ww#...80&bih=804

Regards,

No discussion of simply running a fully redundant duplicate backup of the server? That's what I do.

Rather than buy expensive drives, I just use 2x the cheap ones and periodically mirror my server to a backup box. I keep the backup server unplugged from the wall (power, network, everything) so that if my house takes a lightning strike, the backup doesn't get cooked alongside the primary. No RAID solution is protected from this scenario.

With the price premiums the WD Reds are running right now, it is almost the same price to just double-up on your capacity using cheap(er) drives in an isolated box.

I simply grandfather drives to the backup as I grow the primary. Once a 2TB starts to approach capacity, I replace it with a 3TB drive and send the old 2TB to the backup server.

Truly irreplaceable files (pictures, documents, etc) are backed-up to various media (I have 4x redundancy on that, using the backup server, optical, and external disks).

While losing the media server wouldn't be catastrophic (it's all replaceable), it would be a giant pain in the butt. Thus the backup.

I just picked up a Seagate 3TB from NE for $127 shipped, which is about half of the cost of its WD Red counterpart.

(2012-06-01 01:15)TugboatBill Wrote:  I've used raid 5 arrays in business environments for many years. It's a good technology. It isn't totally safe though, and hardware failures can destroy an array. IE I've seen an array run for years 24*7*365. Then have a HDD failure. Power down, swap out the drive, power up and another drive is dead (translation, the entire array is dead, time for a restore).

So... you're recommending raid 5 because you've experienced catastrophic unrecoverable failure with it?
For me, the striping on raid 5 makes it a non-starter for storing my media. I don't want all of my drives spun up simultaneously while watching a movie - unnecessarily noise/heat/power.

(2012-09-11 01:04)teaguecl Wrote:  

(2012-06-01 01:15)TugboatBill Wrote:  I've used raid 5 arrays in business environments for many years. It's a good technology. It isn't totally safe though, and hardware failures can destroy an array. IE I've seen an array run for years 24*7*365. Then have a HDD failure. Power down, swap out the drive, power up and another drive is dead (translation, the entire array is dead, time for a restore).

So... you're recommending raid 5 because you've experienced catastrophic unrecoverable failure with it?
For me, the striping on raid 5 makes it a non-starter for storing my media. I don't want all of my drives spun up simultaneously while watching a movie - unnecessarily noise/heat/power.

Not because I've seen unrecoverable failures (duh), because it is the best solution in some situations.