Time Machine question

[147798]

I've always had an external drive that (was) a carbon copy cloned of my internal. This allows me to boot from this drive if there are issues with the internal drive.

Does Time Machine (not time capsule, but time machine SW using an external FW-connected drive) allow you to boot from it, if the main internal drive fails? Can you rebuild your main drive from a Time Machine drive?

I'm asking because I'm considering either RAID 1 or time machine, so I'm trying to understand how the sw works.

Thanks.

 

[r.j.s]

You cannot boot from a TM backup, you need the Leopard DVD ... but it will restore everything from your main drive.

 

[upinflames900]

You can't boot from the external drive, but if your internal drive fails you put in the install disk to do an erase an install and then use the time machine disk in the installation to restore all your data. It copies back all of your settings and files to your internal disk when you reinstall so it works well in an emergency.

 

[sidewinder]

I'm asking because I'm considering either RAID 1 or time machine, so I'm trying to understand how the sw works.

RAID 1 is not a backup. RAID 1 offers higher availability. Even if you choose to use RAID 1, you should still run Time Machine or some other backup software.

S-

 

[147798]

RAID 1 is not a backup. RAID 1 offers higher availability. Even if you choose to use RAID 1, you should still run Time Machine or some other backup software.

S-

True, RAID 1 is not a back-up, but if I'm putting my key media files to a RAID 1 drive, isn't it redundantly copied, so if 1 drive fails, I have a mirror on the other drive?

Also on time Machine -- can I use Time Machine to backup both my internal drive AND an external drive (I store my large media files on an external drive).

 

[upinflames900]

True, RAID 1 is not a back-up, but if I'm putting my key media files to a RAID 1 drive, isn't it redundantly copied, so if 1 drive fails, I have a mirror on the other drive?

Also on time Machine -- can I use Time Machine to backup both my internal drive AND an external drive (I store my large media files on an external drive).

Yes you can

 

[sidewinder]

True, RAID 1 is not a back-up, but if I'm putting my key media files to a RAID 1 drive, isn't it redundantly copied, so if 1 drive fails, I have a mirror on the other drive?

RAID 1 is not a backup. Whatever takes out one drive in a mirror could take out the other. Also, if you delete a file or files by accident, they are gone from both drives.

The idea behind RAID 1 is to have redundancy so that if a drive fails, you don't have to take the time to restore from backup. But you should always have a backup. If the choice is between RAID 1 and the backup, go with the backup.

S-

 

[147798]

RAID 1 is not a backup. Whatever takes out one drive in a mirror could take out the other. Also, if you delete a file or files by accident, they are gone from both drives.

The idea behind RAID 1 is to have redundancy so that if a drive fails, you don't have to take the time to restore from backup. But you should always have a backup. If the choice is between RAID 1 and the backup, go with the backup.

S-

Good points. Thanks. I was thinking about it incorrectly.

So, maybe a better setup is to have an external media drive AND a backup drive, given the someone said time machine can back-up both. And, of course, burn key media back-ups to DVD (something I'm behind in doing! -- is there a solution that will burn, say, 21GB worth of iTunes U database across multiple DVDs without have to break up the files yourself?)

 

[147798]

What's the ratio of drive space to time machine space. Is there any compression being used in TM backups?

If I've got a 320GB hard drive, with only about 40GB free, plus say 70GB of external storage. Is a 1/2 TB drive adequate for the Time Machine drive, or do I need something bigger? 640? 1TB?

 

[r.j.s]

No compression.

That setup will work for a little while, but it will fill up quickly, and you won't have much history of changed files.