Time Machine, RAIDs, Partitioning, adding drives?

[roland.g]

I am about to upgrade to Leopard as well as get a Dual-Drive External which can be set as a RAID or JBOD. Not sure if I will get a 1TB now or get a case with 1 500 and get another 500 later. It occured to me that I could just get a RAID and partition it, 1/2 for TM and 1/2 for data. It also occured to me that with 10.5 resizing partitions on the fly that it might be better to partition the RAID so that I can mount the TM and data separately but resize if needed, possibly vacating the data partition if at one point I need the entire RAID for TM and then add another external for data.

1. Will this work fairly easily? Am I getting the resizing of Leopard's disk utility right?

2. If I get a case now and add 1 500GB drive for TM, can I add a 2nd later and RAID the 2 drives, given same specs and models w/o erasing the TM data, i.e. just doubling the space, or does the RAID need to be set up before any data is put on the drive(s)?

Thanks for the input, and any other suggestions.

 

[blodwyn]

Maybe I'm missing something, but it makes no sense to me to RAID the 2 drives into one big one, and then create 2 partitions. RAIDing 2x 500GB drives into a 1TB drive will mean that either drive failing will likely result in all your data being lost, in both the partitions. In this scenario it would be better to just have the 2 drives as JBODs, at least that way if 1 drive fails, the other will still have its data intact

 

[roland.g]

Maybe I'm missing something, but it makes no sense to me to RAID the 2 drives into one big one, and then create 2 partitions. RAIDing 2x 500GB drives into a 1TB drive will mean that either drive failing will likely result in all your data being lost, in both the partitions. In this scenario it would be better to just have the 2 drives as JBODs, at least that way if 1 drive fails, the other will still have its data intact

That makes sense. I was just thinking of it in terms of being able to increase one side vs. another and things like that. And that as long as they were separately mounted partitions, that I could back up part of one to the other just like JBODs. I didn't think at all about drive failure and losing the data from both potentially. Thanks.

 

[compuguy1088]

Maybe I'm missing something, but it makes no sense to me to RAID the 2 drives into one big one, and then create 2 partitions. RAIDing 2x 500GB drives into a 1TB drive will mean that either drive failing will likely result in all your data being lost, in both the partitions. In this scenario it would be better to just have the 2 drives as JBODs, at least that way if 1 drive fails, the other will still have its data intact

What about raid 1, for redundancy, just in case on of the 500 gig drives goes?

 

[blodwyn]

What about raid 1, for redundancy, just in case on of the 500 gig drives goes?

Yes, mirroring the drives will give you redundancy against a drive failure. The drawback is that you only get 500GB capacity out of the 2 drives. Another potential drawback is that doing anything dumb to any files/folders is mirrored to both drives, so it doesn't give any protection against pilot error. An alternative to mirroring is to keep the drives as JBODs and periodically back one up the the other. That way you have a get-out-of-jail-free-card that gets you back to the last time you sync'ed the drives.

To the OP, you don't have to create a dedicated partition for Time Machine. The Time Machine backups are placed in a folder, so you can happily use the drive for other data storage and not have to worry about resizing partitions

 

[compuguy1088]

Yes, mirroring the drives will give you redundancy against a drive failure. The drawback is that you only get 500GB capacity out of the 2 drives. Another potential drawback is that doing anything dumb to any files/folders is mirrored to both drives, so it doesn't give any protection against pilot error. An alternative to mirroring is to keep the drives as JBODs and periodically back one up the the other. That way you have a get-out-of-jail-free-card that gets you back to the last time you sync'ed the drives.

To the OP, you don't have to create a dedicated partition for Time Machine. The Time Machine backups are placed in a folder, so you can happily use the drive for other data storage and not have to worry about resizing partitions

Yes I know about that, though 500GB for time machine has been mentioned in previous threads as a good size. Though for my TM drive I am only using a 160 gig drive....

 

[roland.g]

I think since I have a 750 internal in my iMac I will get the dual case and put one 500 in for TM. At a later point when prices come down a bit and I need it, I can add a 750, move TM to that, and have the original 500 for DV, I can then back up the internal and some of the 500 to the TM 750 since neither the internal nor 500 will be full. While drive failure is a concern, if the TM drive goes down, I replace it and still have my originals, as well if either the internal or 500 goes down, I have my TM drive to restore from.