Can Retrospect Do This? Best way?

[jccrtv]

I'm new and looking at Retrospect for Mac. I need to backup the daily changes to an 8-drive 21TB Raid array each day. I have purchased a second duplicate array of drives for this to be stored in another building. I can set this duplicate array as JBOD and would like to backup the primary RAID array data to the JBOD array each day. Can retrospect do this? Can someone please tell me what Retrospect calls this so I can try it? Multiple Target backup or something? And second question, should I not set the BACKUP array to JBOD?  Iinstead should I make the backup array Raid5 as well? My thinking was: Keep the Primary 21TB Raid5 array for all data, but back it up to a simple BACKUP array as large but that ISN'T raid, just a bunch of OSX drives for simplicity if I need to recover something.

 

Thank you in advance.

[Don Lee]

It is not clear what you are trying to do. How many files? How much changes? Do you simply want to have a remote "mirror" of your primary storage?

 

If all you want is that "mirror", Retrospect is real overkill. If you want real backup, incremental and managed, then Retro may be what you need, but you have to be a little more specific to get a useful answer to your question(s)

[jccrtv]

OK thanks. My need is to backup 21TB of data (about 100 folders). And then each day update the backup with the daily changes. What makes it difficult is the large size. I would be backing up 21TB of data (and the daily changes) from a 21TB Raid5 array (OSX). I would be backing it up to a duplicate array, containing 8 drives (same as the source array). I have the choice to make the destination array exactly the same (21TB in Raid5) or, as just 8 non-raid drives in the array as JBOD. Copying from 21TB raid to backup 21TB raid is simple. But what I think I want to do is NOT make the destination a RAID5, but rather just JBOD as 8 non-raid drives in the rack. My thinking is that I don't need the speed of Raid in the backups drives. And if something went bad it's easier to deal with backup drives that are just non-raid regular volumes. 

 

Question is can Retrospect backup the 21TB Raid (100 folders in one huge volume) over to 8 single drives. I think this is called Drive spanning.

[Lennart_T]

OK thanks. My need is to backup 21TB of data (about 100 folders). And then each day update the backup with the daily changes. What makes it difficult is the large size. I would be backing up 21TB of data (and the daily changes) from a 21TB Raid5 array (OSX). I would be backing it up to a duplicate array, containing 8 drives (same as the source array). I have the choice to make the destination array exactly the same (21TB in Raid5) or, as just 8 non-raid drives in the array as JBOD. Copying from 21TB raid to backup 21TB raid is simple. But what I think I want to do is NOT make the destination a RAID5, but rather just JBOD as 8 non-raid drives in the rack. My thinking is that I don't need the speed of Raid in the backups drives. And if something went bad it's easier to deal with backup drives that are just non-raid regular volumes. 

 

Question is can Retrospect backup the 21TB Raid (100 folders in one huge volume) over to 8 single drives. I think this is called Drive spanning.

Yes, Retrospect can BACKUP to a disk media set with (in your case) 8 members.

But you are talking about a DUPLICATE, which is entirely different.

 

If Finder sees a single logical volume, then you would be OK with Retrospect and duplication.

But for only duplication, I would recommend "Carbon Copy Cloner" or "SuperDuper" instead. Both are competent, can be scheduled, copies only changed/new files.

 

EDIT: I forgot to mention that with a Retrospect BACKUP, you can keep the backups some generations back (depending on drive space).

With a DUPLICATE you would lose the copy if the original file was deleted and the duplicate runs before you notice the file's disappearance. (This is true both for Retrospect as well as Carbon Copy Cloner and SuperDuper.)

Edited July 25, 2014 by Lennart Thelander

[jccrtv]

Thanks. I don't believe either CCC or Superduper can backup one extremely large disk TO across multiple disks. I could be wrong but I tried both.

[Lennart_T]

Thanks. I don't believe either CCC or Superduper can backup one extremely large disk TO across multiple disks. I could be wrong but I tried both.

Right. I should have been more clear about this. If Finder sees a large logical drive from your eight physical drives, then you can use these programs. Otherwise not.

[jccrtv]

OK, thanks for taking the time to help me. Have a good weekend.

[Scillonian]

Also take into consideration that if one disk fails in a JBOD (and RAID0) array you will loose ALL the data stored on the array. With RAID5 one disk can fail and all data will still be intact.

 

Another option to consider is to create a new backup set on the backup array (which ideally should be RAID5 or RAID6) and set Retrospect to do a daily Transfer Snapshots of the changed data. Initially Retrospect will have to copy the full 21TB to the new backup set but after that only new or changed files will need to be copied.

 

I have used this method myself and find it also has the advantage over a Duplicate script that if the original backup set becomes damaged, for whatever reason, the backup backup set should still be usable. I know from experience!