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backup hd failure, what now?


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Hi everyone,

 

I had been backing up several computers on a network with no problems until about 2 weeks ago when one of the external hard drives I was backing up onto failed. The HD is done for and I'm trying to get an idea of how much data will be lost (and, hopefully, recovered). The drive had been filled to about capacity (500 GB) and was the oldest drive being used - there were 3 on a daisy chain.

 

What I'm curious about is how retrospect actually works (I read the manual and am still not entirely sure). I'm including my questions below.

 

*Does retrospect backup all data onto one volume until it is full and then move the the next?

 

*There was retrospect data from the backup set written onto the other 2 HD's but the second was still not filled; is this actual backup data that can be recovered?

 

*If I continue to backup the computers with only the remaining 2 HD's will retrospect recognize the files (if any) already saved on there? Does retrospect need all the files it has stored (such as the catalog files) to operate, or will it try to erase and overwrite them?

 

Currently I am using retrospect 6.1.230. I am using hard drives as removable disks. Like I mentioned earlier, there were 3 drives in a daisy chain.

 

Let me know if there's any more info I can provide. Thanks in advance!

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*Does retrospect backup all data onto one volume until it is full and then move the the next?

With a Removable Disk backup set, each disk volume becomes a sequentially-numbered "member" of the backup set. Retrospect will back up to the first member until it is full, then move on to the second member, etc.

 

*There was retrospect data from the backup set written onto the other 2 HD's but the second was still not filled; is this actual backup data that can be recovered?

If the hardware is fine, you should have no trouble recovering the data stored on that volume.

 

*If I continue to backup the computers with only the remaining 2 HD's will retrospect recognize the files (if any) already saved on there? Does retrospect need all the files it has stored (such as the catalog files) to operate, or will it try to erase and overwrite them?

Retrospect definitely needs the catalog for your backup set. This catalog will have been stored somewhere other than on one of the HD volumes you are using as backup set members. Retrospect will not overwrite the catalog for the backup set unless you perform a Recycle Backup, or unless you recycle the catalog manually in Configure> Backup Sets.

 

What you will need to do is tell Retrospect about the failed member. Go to Configure> Backup Sets> Configure [your_backup_set]> Members. Highlight the failed member and select "Set Missing."

 

Then, the next time Retrospect performs a backup, it will back up anew those files that were on missing member #1, provided of course that those files still exist on your source volumes.

 

As you've found out, backups are useful only to the extent that the backup media remains intact. Because all media will eventually fail (if at some point far in the future), it's important to perform backups to multiple backup sets so that you have redundant copies if/when a media member becomes unreadable. There are a number of strategies for doing this, some of which are discussed in the User's Guide. Let us know if you'd like some suggestions from this group as to what we're doing.

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  • 2 weeks later...
  • 1 month later...

To achieve backup redundancy, you need at least two separate backup sets on physically different media; we use three. You then need to establish a schedule that rotates among your various backup sets. More frequent rotation means that you won't lose as much new data if a particular piece of media is damaged, but also means more work and inconvenience in swapping out the backup set media, especially if you always take care to keep one of your backup sets off site. Only you can decide what's the appropriate tradeoff between safety and convenience.

 

In our case, we have chosen to run backups seven days a week and to rotate sequentially among our backup sets every weekday, so that we won't lose more than one day of new data (or up to three days over the weekend). Our scheme requires 15 different schedulers in the backup script because the backup pattern repeats only once every three weeks. A simpler arrangement might rotate between two backup sets on alternate weeks or use one backup set for Monday-Wednesday backups and a second for Thursday-Sunday.

 

We perform a New Media backup whenever the backup set becomes inconveniently large to perform restores. (We back up to tapes and retain all of our old backup sets so we can recover ancient data as needed.) If you plan to use file backup sets, you're more likely to be performing a Recycle Backup when the destination volume approaches being full, though you could always choose to introduce a new media volume and store the previous hard drive volume for a while. If you do recycle your backup sets, don't recycle both at the same time; alternate your recycling so that you always have at least one complete and reasonably recent backup at all times.

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What are the benefits of backing up onto tapes vs. hard drives?

Tape cartridges are less prone to fail when dropped than are disk drives.

 

The density (per volume) is higher on tape.

 

Over time, you might lose the ability to connect a computer to a disk drive as connection technologies evolve (IDE, ATA, SCSI, etc.) but tape is tape.

 

Also, is there anyway to dictate what external drive a backup set saves to?

yes.

 

Russ

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Thanks for the help.

 

How would I go about telling retrospect where to save each backup set? Say I have two backup sets, backup set A and B. I have two external drives as well, backup 1 and 2. I want backup set A to save only to backup 1 and B only to 2 so I can make redundant copies of all my files and switch backup sets weekly. How do I set this up?

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Yes, I see that you can choose the destination backup set. I have both selected and have two different scripts set up to run on different weeks. However, the only destinations I am allowed to choose are the backup sets. When I click on these sets I get the options for that particular backup set, but there is no option I can see to pick the target media (the 'Media' 'Action' button is grayed out in the 'Options' tab. How did you access that choice? Can you list the menus/buttons you went through?

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You select the backup set and its target the first time you choose the destination. You did it correctly at one point long ago because you indicate that you were previously backing up to disks that died.

 

Simply make a new backup set and choose it. Your old one is gone because the disk died.

 

Do you really want me to specify each mouse click? This is really basic stuff. Click the Destination button, Add a new backup set (your new drive), choose appropriate options for that backup set, then, in each of your scripts, choose that new backup set rather than the old bad one.

 

Perhaps you are thinking that you are somehow going to change/modify your bad/gone backup set. Nope, you make a new backup set A (or whatever you are calling it) and target your new drive for that new backup set as the destination.

 

Russ

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