Some basic RAID questions? - DPChallenge Forums

04/30/2009 11:31:24 AM · #1

I'm looking to expand my back-up capability now that I have a digital video camcorder. I'm thinking a RAID array would be appropriate and storage is pretty cheap these days. A few questions:

Can all external hard drives be used in RAID arrays or do I have to look for something that says RAID capable?
Leaving the price aside, what are the pros and cons of a 2-drive RAID 1 array and a 3-drive RAID 5 array?

Prof_Fate

04/30/2009 11:45:39 AM · #2

RAID is Redundent Array Of Independ Disks.
So you need more than one disk or it can't be raid. (duh, huh?)
Almost all raid systems need the disks to be all the same disk size (and same brand/model helps too)

You have MIRRORing (RAID 1)- two drives that are identical copies of eachother. You need 2 1Tb drives to get 1Tb of storage, but you have 100% copy protection - so it's instant to keep going if a drive fails.

You have Raid 5 where 3 or more disks have the data striped across them with parity so you can rebuild the data if any one fails - but that takes time to do of course. It should be faster to read/write than mirroring but what's theoretical, what really happens and whether you can even notice are all different things. 1 of the three disks is used for parity so 2/3 of the total capicity is available for data - you'd need 3 500Gb drives to get 1Tb of usable storage.

You need a RAID controller - these can be built in to many mobos or you can get a card to add it, or get an external device of which there are several.

DROBO is interesting in that you can mix and match drive sizes and types, etc - BUT it's totally proprietary in design - so if it fails you need to buy another just like it. "Normal" raid drives could be plugged into a RAID capable PC and you can begin working. I've also talked to a number of people that seem to have a high drive failure rate with DROBO. But it does allow painless expansion.

Almost all external drive solutions will be slower than what you can put in your main box - and moving large amounts of video that's a consideration.

So, pros and cons...I went with mirroring as there is no downtown, no wizardry happening,etc. Simple. Less hardware to fail, less cost, etc.

Can external drives (as opposed to bare ones) be used in RAID? I have no idea - I would think not though.

smardaz

04/30/2009 11:50:29 AM · #3

hey doc,

you can use usually use one external drive if your motherboard has an e-sata connector but that is lame and sucky. Almost all modern motherboards will support raid 1 which is really easy and gives you redundancy with hot swap capability if one drive dies

Message edited by author 2009-04-30 11:50:43.

Canon RF 24-70mm f/2.8 L IS

04/30/2009 12:16:17 PM · #4

So it's the controller not the disk that allows for the various RAID types? RAID 5 strikes me as overall more efficient since you only lose 1/3rd of your disk capacity (on a 3 drive array), whereas RAID 1 loses 1/2. But maybe less controllers allow for RAID 5?

kirbic

Canon EOS R5

04/30/2009 12:39:17 PM · #5

Originally posted by DrAchoo:

Yes, the controller is the determining factor. As Prof_Fate posted, you should (and may have to) use the same drive type across the array, but otherwise the drive is not a determining factor.

Many on-board RAID controllers only allow RAID 0, & RAID 1. Add-in RAID controllers are usually much more full-featured. Unless you have a lot of internal space and cooling, though, RAID arrays with three or more drives are not that practical.

An external storage solution that incorporates RAID is an alternative, but of course they are more expensive and you have the potential performance penalty of pushing bits across a network or other external protocol.

My personal strategy is to use one large internal drive, periodically (and automatically) backed up to an external drive of matching size. No RAID involved.

smardaz

04/30/2009 12:47:06 PM · #6

Originally posted by kirbic:

My personal strategy is to use one large internal drive, periodically (and automatically) backed up to an external drive of matching size. No RAID involved.

thats assuming people remember to back up,or know how to autoimate it. RAID 1 is very easy and if you get a couple 1/2 tera or 1 tera drives you wont be as affected by the loss. Also I have tried to buy raid 5 cards before and they are NOT CHEAP. Did you build your pc doc or have it built? if you have the book for the motherboard, it should tell you how to set it up. Easiest to do it on a clean install of windows

Message edited by author 2009-04-30 12:47:46.

shanksware

Canon EOS-5D

Canon EF 85mm f/1.2L II USM

04/30/2009 12:48:54 PM · #7

Just for the record...

We have had the Drobo for more than a year.
It's been on almost 24\7 since we got it.
No problems whatsoever.

We have 2 bays filled with 1TB drives.
It's now 37% full.

We have it networked using the Droboshare so we can get to everything from any PC in the house.

I'm very pleased.

Canon EF 100-400mm f/4.5-5.6L IS

04/30/2009 12:49:17 PM · #8

Ive bee building file servers for years for my personal and business use and now am the proud owner of 3 Drobo's and OMG they are soooo nice, By far better than almost any raid Ive used thus far. They are nice as they are easy to set up and self contained. And you don't need to match drive brands or sizes in them just drop in what ever you want and it takes care of the rest, the drives are all hot swappable so there's no down time and the other cool thing is if a drive fails or something goes wrong you can set it up to shoot you an email which is a sweet feature :)

-dave

Strikeslip

Canon EOS-5D

04/30/2009 01:27:44 PM · #9

This Network Attached Storage (NAS) might interest you. This is the one I have, but there are some different flavours.

Jedusi

04/30/2009 01:35:45 PM · #10

If you want to go for something cheaper - I've been using the WD Mirror for about 8 months now and it's been good as gold.

No NAS capability though. WD MyBooks seem to do NAS or RAID rather than both. I've had mybooks for some years now and they have always been really good.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

04/30/2009 02:07:21 PM · #11

The Drobo sounds pretty cool. I like the expandable at any time part and that you don't have to match HD sizes. What are the downsides other than the cost? How efficient are you with your space? I assume you need at least 2 HDs before you are really protected from a HD failure.

rich

Canon EOS-40D

Canon EF 50mm f/1.4 USM

04/30/2009 02:17:31 PM · #12

Originally posted by kirbic:

My personal strategy is to use one large internal drive, periodically (and automatically) backed up to an external drive of matching size. No RAID involved.

I use the same method as Kirbic - large internal drive backed up to an external nightly. Even for people who don't work in IT it's not that difficult to set up an automated backup schedule to copy files to an external hard drive given that the software comes with Western Digital E-Books and the like. And most of us know a friend or two that can spare 15 minutes to help out a pal to set this up.

There is another added benefit to this strategy, aside from low cost - offsite protection. If you use two external hard drives for backup, you can keep one of them locked up somewhere securely offsite which protects you from the total loss caused by fire or theft. RAID systems are great, but they don't protect against either of those scenarios. The biggest advantage of a RAID system is that the fault tolerance is realtime - if you lose a disk, you should have all of your data protected up to the minute. But if you are OK with a nightly backup schedule, losing at most one day of data, Kirbic's solution is worth a look. Especially if you want to have backup, both local and offsite, at a relatively low cost.

Citadel

Nikon D7500

04/30/2009 02:33:48 PM · #13

There are some caveats to remember or at least consider with RAID.
1) If your house burns down it doesn't matter what RAID system you are using. If you don't have an off site back up its gone
2) If you delete a file by mistake it doesn't matter what RAID system you are using. Its gone. (Unless you have a copy elsewhere).

Lesson: RAID helps protect one copy. Additional offsite backups are always a good idea.

That being said? I have a copy of my files on my PC and another copy on a D-Link NAS. So if I delete a file by accident I am covered. If my house burns down? I'm screwed. Maybe I should practice what I preach....

Message edited by author 2009-04-30 14:34:29.

04/30/2009 02:39:57 PM · #14

Well, how about online storage backup options then? Anybody know the cost of a system that can backup a 1TB drive online?

There are some catastrophies that are rare enough that the cost of protection outweighs the benefit. If the whole house burns down, then I'm more concerned that my family gets out alive. How many of us "backed up" slides and prints and negatives and kept them at a separate site? None...

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

04/30/2009 02:47:34 PM · #15

Originally posted by DrAchoo:

I have to watch my space very closely as the photos don't take up a lot of room but the 3D animations can hit a couple hundred gig easily and yes as even with a RAID mirror you need at least 2 drives to start off with.

I have yet to find a down side to the Drobo's, when the photos come off the flash cards I send them directly to the Drobo which is across my gigabit network connected to another PC and edit the photos right off of the shared Drive on the network with acceptable speeds. I haven't tried the fire wire on my 2nd gen Drobo's but imagine it would be a tad bit faster than the USB. The initial startup cost for the Drobo can be a bit pricey but a "GOOD" Raid card will easily cost you as much if not more. I had a 4 port SATA 3ware Raid card that was rock solid and love it but its also about $500 plus I need a PC to plug it in to.

I was on their site not long ago and noticed they have a DroboPro which Ive been drooling over but can imagine the cost of that one will be cdn $800-$1000 but like I mentioned a good RAID card and a PC will cost more easily...

Ive gone through many types of Data backup and now with the photography, to loose even just a few photos can be devastating esp if they are from a wedding or the like that you are hired to shoot, you cant recreate that so you are pretty much screwed. I always work off of and back up to Mirrors and or units like the Drobo's. You loose enough data you will understand and the client NEVER will understand if you loose their job due to drive failure and even if they do understand they wont care for anything but the fact it was your fault. I currently manage for my own business and persona data about 14TB or 14,000GB of files to give you an idea, not everything is on Drobo's but Im slowly going that way as they have been AWESOME for me the past couple years.

Just food for thought.

-dave

Citadel

Nikon D7500

04/30/2009 02:50:46 PM · #16

Originally posted by DrAchoo:

Very true. In terms of external backups, the president at my local camera club actually just uses two 1 TB external drives. One is at his house (he uses it for a second backup), the other is in a safety deposit box. Every couple of weeks he swaps them. So he has 3-4 copies of every file (depending on if the shot is on both external backups). That might be overkill for most people but then again, I think its up to the individual to decide how much protection they want. And of course he's not protected if a meteor hits Calgary. (In which case, who cares about showing off pictures?) :)

By the way, I haven't tried the online backup solution myself though I have heard that it is relatively inexpensive and the site takes care of data protection on their end as well.

04/30/2009 03:31:06 PM · #17

Wow just checked my local supplier and the DroboPro is $1599.99 O_O (thats in Canadian Dollars)

But for the rest of us mortals the normal 4 drive version is rock solid :)

04/30/2009 04:00:45 PM · #18

what happens if the drobo itself fails? Do you just get another and plug your HDs in and off you go?

04/30/2009 04:15:32 PM · #19

Originally posted by DrAchoo:

what happens if the drobo itself fails? Do you just get another and plug your HDs in and off you go?

Yes basically, you would take the drives out and once you have the new unit, BEFORE you power it up you put all the drives in the new unit and then fire it up and it will continue on as nothing has happened. This works as I have tested it across all 3 of my Drobo's 1 first gen and 2 second gens... and yes Im very paranoid over my data lol.

-dave

04/30/2009 04:20:58 PM · #20

I think I'm pretty sold.

Jedusi

04/30/2009 04:28:08 PM · #21

Originally posted by DrAchoo:

The Drobo sounds pretty cool. I like the expandable at any time part and that you don't have to match HD sizes.

not strictly true of course - for maximum efficiency you obviously need paired drives of the same size. You can't mirror 1gb data onto a 500mb drive. But that's pretty obvious.

I have to admit that while I'm very happy with the WD solution I also have looked at - and like the Drobo solution. However the cost does start to add up when you buy the Drobo, then have to buy the drives to put in it. I know of some people who just buy a cheap PC unit - throw an additional hard drives in it and tuck the base unit away in a corner. It is already NAS capable, has it's own OS & on board memory and doesn't need much to run raid.

Message edited by author 2009-04-30 16:28:50.