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Author Topic: Filesystem Backup Strategy  (Read 1839 times)
jlpoole
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« on: April 05, 2010, 09:51:53 AM »

I had previously posted that I had mounted an external hard drive (Seagate external 1.5 TB) and mapped my /var and /usr to the drive.  I have two identical drives and had intended to create a back-up strategy.  I had not implemented one (6 months down the road) and, of course, the hard drive that I have the data mapped to has a malfunction rendering my plug inoperable for the moment.

I'm looking into what might be done to recover the data and it appears to be a minimum $500 charge. 

I posed the issue of drive manufacturers providing data recovery on reddit when their drive fails and the unified response was pretty much: I'm a dumbass and should have had the data backed up, presumably by RAID.  (I've been researching the issue and it looks like an external RAID controller exposed as a USB drive would be the safest solution; you're then placing your data at risk of the design/implementation of the RAID controller, some of the cheapest ones seem to have postings on forums of completely losing their data.)

Given the SheevaPlug's design of not having internal drives and a linux community's opinion that back-up is a requirement, I wonder what people developing on the SheevaPlug do for their back-ups.  Seems that if you are using a hard drive, you probably should use two (as I did, but never configured as I planned) to protect yourself when one goes bad.  In another posting to this forum, the opinion was a software RAID is unacceptable, and I"ll agree with that opinion.

So what are people doing who attach hard drives to the plug?  Or is the safer course using multiple stick USBs and not having a lot of data? 

I guess what I'm thinking is that if you are using an external hard drive, it must be in conjunction with a backup system.

« Last Edit: April 05, 2010, 10:06:36 AM by jlpoole » Logged

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fragfutter
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« Reply #1 on: April 05, 2010, 10:45:59 AM »

the idea of having a softraid is not bad in itself. But having a softraid over two USB Drives is bad. USB is (in my opinion) not reliable enough and doesn't handle the load.

I recommend using rsnaphot (http://rsnapshot.org/) and a second drive for peridoic backup. I have two removable sata drives in my primary computer. Every time i think about it i push one in (alternating) and run a shellscript sitting on the disk. It pulls backups of all important data using rsync. Data on the sheevaplug is pulled over the network. Gigabit Network is fast enough for that.

To have a real backup (meaning more then one generation) your backup disks should be bigger then your live data.

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rooster
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« Reply #2 on: April 05, 2010, 10:46:43 AM »

First of all, I would try SpinRite v6 http://www.grc.com/intro.htm, it is what the repair shop use before opening the drive.

About backup:
I backup all my family photos to Amazon S3, cheapest cloud for users that do not backup HD videos. Other alternatives are Carbonite (unlimited bandwidth, fixed price), Mozy...
I have another backup made of all audio video and photos to another DAS (same size) that is @ work, which I backup once a month.
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superpat
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« Reply #3 on: May 03, 2010, 06:30:24 AM »

Hi,

I looked at this problem several years ago and at first I too thought I needed a RAID storage system, so I built one using 4 x 500GB Sata drives and a 4 tray hot swap unit, I put them into a m-itx case, lots of cutting and filing,  and drove it with a Via m-itx card. I use FREENAS as the operating system.  (Picture attached below).

After a few months I came to realize that the RAID system  (IN MY USAGE PATTERN)  was unnecessary, noisy and a power hog.

The reason for this is that I store large quantities of data that are only updated intermittently at long intervals. 

My data consists of Squeezeserver files (running under FREENAS) and photographic files.  There are also periodic backups (monthly) of my wife's and my Linux user home  folders.

So I normally use one one of the 4 500Gb drives on the NAS and when the data changes, ie new photos or a new CD to put on the Squeezeserver,  or weekly whichever is the shorter, if I add another gig of photos, I turn on another of the drives and let FREENAS do a Rsync update of the data to the second disk.   I then have TWO identical copies of data not more than a week stale.  I always check the target after adding data.

I suppose I should remove the second copy drive from the FREENAS and store it in another location but I am not that paranoid (yet).

I cannot emphasize enough the necessity for backups!!!!!!!!!

A couple of months ago a neighbour came to see me. She had given her daughter an old PC 3 years ago, and the daughter and her husband had used it constantly without backing it up.  One day the hard drive ceased to function.

They thought they had lost her husband's small business data, their household data, and ALL the pictures of their family and of their two children from birth till the drive crashed.

I was asked to try to recover the data.  Using a shareware Windoze disk recovery program, ($20) I found that the drive was still reading, but the directory structures had been destroyed.  After 10-12 nerve wracking hours, I managed to recover all the data, albeit with dummy file names. I stuck the files on a load of CD's and they put a new drive in their PC and reloaded and renamed all the files.

I received two bottles of wine for my effort not $500! They did pay for the recovery program.

I told them to back their data up in future, but I wonder whether they really are doing it or whether we will be going through this excerise again some day!

As usual YMMV

cheers

Patrick

edit replaced picture with a resized version kindly creaed by jlPoole.


* pat_raid_server.png (126.14 KB, 360x241 - viewed 356 times.)
« Last Edit: May 06, 2010, 01:55:39 AM by superpat » Logged

obarthelemy
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« Reply #4 on: May 03, 2010, 10:32:46 PM »

Raid is NOT a backup. A backup is
- off line
- off site
- tested
- multiple

Raid is none of that. Raid is:
- more speed
- more capacity
- high availability
- sometimes, ability to enlarge volumes w/o reboot.

Quick check: what does raid protect you against, among the following:
A- single-disk failure
B- System destruction or theft (fire, flood, power surge...)
C- Operator error
D- Virus
E- File corruption (App error...)
F- File system corruption (OS bug...)

Answer: A)... for ABCDEF), you need a real backup...
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peter a
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« Reply #5 on: May 03, 2010, 11:41:01 PM »

A ? , it all depends on which Raid level.

So with Raid 0 you can have a single-disk failure ? , I think not

  more speed 
  is a big ? on any raid level if it`s software Raid ?
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