Backup with Time Machine on 2 different Hard Drive

I'd like to know if I can backup *all my data on 2 different external hard drives*. The aim is to a double backup in case of big issue.
I'd like to process on this way:
- only one of my backup HD at home and the other is at the office
- when I plug one of the backup HD, its data is updated according to the previous backup with this HD (not with the other one)
- if I backup my MBPro just before leaving the office (on the office's HD) and I backup my MBPro just after arriving at home (on the home's HD), my 2 HD should have the state and exactly the same backuped data.
Is it possible ? Otherwise, is there another way to proceed ?
Thanks for all,


*Using Time Machine with Multiple Destination Hard Disks*
Yes, this is possible, as long as you understand how it works. First, Time Machine is only designed to work automatically with one backup disk. If you are going to employ multiple Time Machine disk with a single Mac, then you are going to have to manually select the new drive each time it is attached using the Time Machine Preferences “Change Disk…” button.
Secondly, Time Machine *+does not+* ordinarily perform file-by-file comparisons to determine what has changed and thus determine what needs to be backed up. Rather, Time Machine relies on FSEvents notifications. This is a log that the system uses to keep track of changes to directories. Rather than scan tens of thousands of files for changes each time, Time Machine simply looks at this log and narrows its’ scan to only the directories that have experienced changes since the last backup.
Every event that FSEvents records has its’ own ID which includes a time stamp. At the end of every backup, Time Machine stores the last event ID that it processes. When the next backup is initiated, Time Machine looks at this stored ID and determines that it only needs to backup events that have occurred after the time stamp on this last event ID.
Naturally, for hourly backups, Time Machine does not have to go back very far to find the last known event ID. However, if a Time Machine disk is only being attach for backups every few days, a week, or more, and Time Machine has to go back too far to find the last event ID, then it will give up and simply go into “deep traversal” and do the file-by-file scan on its’ own. There are simply too many events logged by the system for Time Machine to bother looking for the last known event ID. Consequently, expect lengthy “Preparing Backup…” sessions anytime you attach a backup disk infrequently.
Nevertheless, using Time Machine with multiple destination disk will work. If the two drives are routinely backed up then they will always remain in relative sync.
Finally, remember to reselect your normal Time Machine disk in the Preferences when the backup to the secondary disk is complete.
Hope this helped clarifies things a bit for you.

How to do a backup with time machine?

Hi Communitieee, I dont know how to make a backup with time machine. Can anybody help me? And i have another question.. whats wrong with library? when i start my mac the message is popping up but i dont know what it means.. Thanks KROk thanks mende1.

Time Machine on an External Hard Drive - used with another computer or mac?

I'm planning on selling my computer but want everything that is on my Mac saved so when I can afford to buy a new computer I will have all of my files, music, pictures, etc.  I hooked up Time Machine to an external hard drive last night.  So everythi

Wireless Backup with Time Machine using Fritzbox

I have Modem: Fritzbox 7170 Macbook white Lacie External HD 500GB On the back of the Fritzbox is an USB access..I would like to connect my Lacie External HD to the Fritzbox and want to split the HD into 1 part to store my music/photo's on 2nd part to

HT3275 Since updating OS to Mountain Lion from leopard, I get the following error message when trying to backup with time machine on external drive.  Could not complete backup to media share.  The network backup disk does not support the required AFP feat

Since updating OS to Mountain Lion from leopard, I get the following error message when trying to backup with time machine on external drive.  "Could not complete backup to media share.  The network backup disk does not support the required AFP featu

How do I move data on time machine from one external hard drive to another

How do I move data on time machine from one external hard drive to another?Although the documentation says you can copy Time Machine backups in the Finder, it's very slow and sometimes doesn't work at all. Launch Disk Utility, open the built-in help,

HT3275 Time Machine says my external hard drive does not have enough

Time Machine says my external hard drive does not have enough space for the current backup.  It needs 34 G out of a 250G hard drive.  All that is on the drive is earlier backups.  I recently added memory, which may confuse Time Machine into thinking

Backup with time machine

I backup my Aperture Library with Time machine. When I work on a picture, does TM back up just this picture or the whole Library??I came on this thread via Google, and it's less than 2 months old, so hopefully I can resurrect it justifiably. I notice

What's a reasonable amount of time for time machine to "prepare" a hard drive?

I'm trying to put my time machine backup onto a new 3TB external hard drive (my iMac has 500Gb of data).  The first external drive said it would take 11 days to back up.  After it was running for 3 days I asked an apple genius how long it should take

Time Machine backing up external hard drives?

I have a Macbook Pro connected to two external drives.  One is a simple 2 TB drive and the other a 6TB RAID1 drive.  Before I switched from OSX 10.6.8 to Mountain Lion, Time Machine appeared to back up both the MacBook Pro and the external 2TB  drive

How do I connect both iMac (2011) hard drives to backup with Time Machine and Airport Time capsule?

Hi - my iMac has 2 hard drives, 250 Gb solid state and a 2 Tb drive.  I'm backing up using time Machine to an Airport time Capsule but only the 250 Gb drive comes up in hte list?  All my photos are on the 2 Tb drive (about 120GB worth) and I want a b

Unable to keep my external hard drive connected to my computer for backup with Time Machine.

I am using an external LaCie hard drive to backup my computer.  In the last month or so I have noticed that when my computer is in the sleep mode for sometime the hard drive disconnects from my computer.  I than get an error message that tells me tha

No longer able to backup with Time Machine

I have backed up my 2.93 GHz 640 GB iMac with 4 GB of memory for years to a 1TB external drive via Time Machine. I'm using OS X version 10.7.5.  I've started to run out of space on the iMac so I got a 2TB external drive to move my photos to.  Before

Can I use my 1TB Time Capsule as my external HD AND have it do backups with Time Machine?

I want to be able to utilize my Time Capsule as my external HD because I have 150GB of photos and music to offload but it's unclear to me how to do this - it seems that some say that it can only either do Time Machine backups (that eventually would d

Kernel error on startup after trying to backup with Time Machine

Hi there, So last night I was using time machine to back up my macbook hard drive to my external hard drive. As this was happening, my machine was slowing down and such which I attributed it to having a couple of programs running at the same time as

Restoring from Time Machine to an external hard drive

I had a hard drive crash on a MBP and am using DiskWarrior to try and recover it.  DW has been running for over 48 hourse and says "speed reduced by disk malfunction: 3,177"  (the number increases every few minutes)  The DW folk tell me to give

Time Machine cannot find external hard drive

I have just recently purchased an airport extreme and have enjoyed being able to plug in an external hard drive for time machine. I think I must have reset my laptop while it was backing up because now I get an error every time it tries to back up. T

Using time machine to format new hard drive

Hi there, hope this is a relatively easy question! Long story short, my macbook pro's harddrive recently decided to stop working. I will being installing a new one in the next few days. I've made a bootable USB drive with Mavericks on it, however my

Macbook pro won't restart after time machine install on new hard drive

I installed a new 500 GB HD on my 13-inch mid 2010 Macbook Pro (since the original crashed).  I successfully connected to the Disk Utility via the internet connection and started recovery from a recent Time Machine backup....but, the computer will no

All applications were "?" On the dashboard after time machine restore to new hard drive...what went wrong?

Hi folks I used the cmd R option on booting the MBP and did a disk scan and it reported errors that could not be fixed/repaired. So I opted to install a brand new 1Tbyte Seagate hybrid hard drive and restore from my time machine backup. So I installe