Raid 1 / Raid 5

[Pete Suttner]

Hi, I'm considering external storage options in the 4 terabyte range. Firewire 800 for archiving scans. What are your thoughts on Raid level?

[Ron Marshall]

Depends what you are trying to achieve: greater speed or redundancy?

http://en.wikipedia.org/wiki/RAID#Standard_levels

[Pete Suttner]

Redundancy.

[Ron Marshall]

RAID 1 then.

[SergeyT]

Make backups and keep them away. Cheaper and more safe.

[Darren Kruger]

Hi, I'm considering external storage options in the 4 terabyte range. Firewire 800 for archiving scans. What are your thoughts on Raid level?

With RAID 1, you only get to use 50% of the raw space of the drives. But it is very easy to get back going if a drive fails. RAID 1 by itself doesn't combine the space across drives. For that look for RAID 1+0 (sometimes listed as RAID 10).

With RAID 5, you get better space utilization as you only lose one drive's worth of space over the full array. If you have four drives you would have free space equivalent to three. Reads and writes are across multiple drives for a possible performance boost. Cards that support RAID 5 are more expensive.

RAID 1 requires at least 2 drives. RAID 1+0 requires at least 4 and RAID 5 requires at least 3 drives.

are you sure you need RAID support for external storage for archiving scans? There is something to be said to having multiple copies of the same data on different disks and then storing one of those copies offsite.

-Darren

[JHenry]

Pete.

Take a look at Drobo (www.drobo.com). This is what I use. Initial cost is a bit higher since you have to buy the device. But, for ease of use and redundancy, I find it to be great. Also, it is perfect for the non-techie who just wants the ability to do easy and automatic backups, with the ability to scale up if/when needed.

Of course, this keeps a complete backup of everything onsite. For absolute true backup, I'd occasionally make a back up of all my files onto an external hard drive and keep it offsite.

Cheers,

Jeff

[Richard Mahoney]

Hi, I'm considering external storage options in the 4 terabyte range. Firewire 800 for archiving scans. What are your thoughts on Raid level?

RAID 1 with hot swap drives and automatic failover to pre-assigned standbys: dead drives can be pulled and replaced at *your* convenience not when the inevitable failure occurs. Get the best drives you can afford, always cheaper in the long run. I'm still using a set of 4-5 year old 15K Ultra-320 SCSI disks and they haven't had an easy life. They should be nearing end of life for server disks. I'll probably be replacing with SAS drives when they finally cark it. Redundant disks are only part of the story. Off site storage is a must. For a relatively cheap and simple solution Amazon S3 should be your friend.


Kind regards,

Richard

[Darin Boville]

Redundancy.

Then you have to ask "why"?

If you are trying to insure against fire or theft--or lightning hitting the house--then all that RAID business is just more consumerism. The geek's version of the Viking oven.

I use Time Machine + periodic back ups that are kept in my car. I keep taking about copying my photos, (especially the good ones!) and sending them out of state--I really should do that given that I live on a fault network...

--Darin

[mhanc]

Belt and suspenders:

1. Time Machine back up 2nd drive. Good for file recovery - can be used for disaster recovery.

2. CCC (Carbon Copy Cloner) for periodic complete disk backups to 3rd drive. Good for disaster recovery.

[Pete Suttner]

Part of the beauty of shooting film is the negative for fall back. I wish I could say that all my shots were keepers but I only keep a percentage of what I shoot on disk. I develop and scan (no enlarger). Trouble is as I see my 1 TB main and internal back up space evaporating. So I scan everything except dogs, then rely on my initial impression for keepers. I'd like to be a little less conservative about what I save i.e. external storage as a giant proof sheet.

Thanks for all the input...

[domaz]

Then you have to ask "why"?

If you are trying to insure against fire or theft--or lightning hitting the house--then all that RAID business is just more consumerism. The geek's version of the Viking oven.

I use Time Machine + periodic back ups that are kept in my car. I keep taking about copying my photos, (especially the good ones!) and sending them out of state--I really should do that given that I live on a fault network...

--Darin

In your car? Large swings in tempearture common in the car + bumpy roads = very bad place for hard drives. Unless they are laptop hard drives that is- those are made to withstand higher G forces and temperature swings.

[LF4Fun]

very good explanation & more from gizmodo (http://gizmodo.com/5203952/giz-explains-what-a-raid-hard-drive-array-is-and-why-you-want-one)
:)

[Darin Boville]

In your car? Large swings in tempearture common in the car

You've obviously never lived in Montara :)

--Darin

[tlitody]

what richard mahoney said except buy yourself a small fire safe which is waterproof as well as fire proof and providing is is bolted to the floor, your disks can be kept as safe as offsite and its a lot less hassle.
Short of a very determined thief you won't lose anything.

[domaz]

You've obviously never lived in Montara :)

--Darin

I'm pretty familiar with stable Pacific coast weather patterns but surely the sun comes out sometimes in CA- it even does here in Puget sound. And once the sun comes out temperatures soar in cars. Then at night things cool down again. Not even to mention the physical security aspect- how often do car break-ins happen in your area? Would you like a theif to have a backup of everything that is important to you?

[Darin Boville]

I'm pretty familiar with stable Pacific coast weather patterns but surely the sun comes out sometimes in CA- it even does here in Puget sound. And once the sun comes out temperatures soar in cars. Then at night things cool down again.

Well, there was a day a couple of years ago when it hit 80 degrees, or nearly so. And I also remember a day when I first moved here six years ago when there was frost on the cars in the morning...


Not even to mention the physical security aspect- how often do car break-ins happen in your area? Would you like a theif to have a backup of everything that is important to you?

We had a kid opening unlocked cars a year or two ago to get money to buy drugs. That was a bummer. Can't think of anything else offhand...



Would you like a theif to have a backup of everything that is important to you?

As long as I still have a copy, all is well....

--Darin

[Lenny Eiger]

I suggest RAID 10. The great thing is that drives are so cheap nowadays. 1-1.5 TB for less than $100.... The thing that's great about mirroring is that you can take a drive out of the pack and put a new one in without missing a beat. The software will usually create a new mirror automatically. This allows you to take a hard drive or two and put it somewhere else like a safe deposit box away from your home.

The idea of a "copy" is ludicrous, especially if one means a DVD, as they last only a short while. I would only use them for transferring. Further, firesafes will not protect against melting plastic. Their primary function is to keep the temp below 451 degrees. Plastic melts, including dvd's, possibly negatives, at much lower than that.

I would go with RAID 0 or 10. I have had a good experience with using SoftRAID, and Sonnet cases.


Lenny

EigerStudios

[IanMazursky]

I have been using raid systems in various forms for years and they are great. I wouldn't store my production data any other way.
The striping versus mirroring versus raid 5 is a long debate but here are my views.
With striping if one drive goes, your SOL without a good backup.
Mirroring is ok but you don't get the speed improvements of striping and youre basically wasting a drive.
And to top it all off, if the drives are from the same manufactures lot, they could both die around the same time.
Been there done that...not fun at all. Ive talked to IT guys at fortune 500 companies and they usually buy drives from different lots.
Its a good practice but sometimes hard and expensive to do.

Im also a big fan of external hardware arrays, anything that is software driven can have some serious complications.
If your computer takes a bad hit, it could damage the array. If you need to move it from one computer to the other, you have to hope that it will come back up.
The software could have a glitch when you update it, problems with an OS update and software raid....too much risk for a little savings.
A few years ago I tested a software raid on a test box, i ran into some of those problems and it confirmed why i don't use software raids in production.

I gave up on software raids years ago. Im a raid 5 man all the way. Its the best of both worlds.
One of the best parts is that if your enclosure supports hot swapping, then when a drive dies you can replace it while the array is live.
You can continue to work while its rebuilding. Ive been slowly replacing the 8 drives in my array as they start to fail. A very useful feature.

All of that said, nothing is better then a good backup. Even hardware raids will eventually fail or you will delete or overwrite a file.
I invested in a LTO tape drive and a lot of tapes. Cost per GB is very low and the tapes have a 30+ year lifespan. Cd's/DVD's and hard drives don't.
Well spinning hard drives don't. Thats the problem with disk to disk backups. Live drives have a MTBF (mean time between failure) of 5-6 years.
I can confirm that some of the manufacturers mean it! Others seem to last and last and last. I have some drives that are going on 15 years.

Portable hard drives are also not a good way to store data. They are subject to more wear and tear then fixed drives.
Case and point, a few years ago my laptop drive died after 2 years, same with my sisters. I had a few firewire portable drives that only lasted 1.5 years.
Although that pretty good for bouncing around in my bag.

I guess the moral of the story is do what you can afford but keep multiple backups in multiple locations.
Then as the backups near the end of their lifespan, move the data onto newer technology and keep it going.