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Mathemagier

Disk0-to-Disk1-to-Tape: Overwrite Disk1

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Hello, this is my first post, maybe you can help me.

I own Retrospect 8.5 and want to configure a Disk-to-Disk-to-Tape backup as follows:

 

  • Source Disk0 is a set of 10 external 2TB HDDs
  • Disk1 is a Raid 0 array with 4TB
  • Destination is an LTO-5 drive

I have 2 catalogs, one for each process.

  1. First process is to backup all source disks to Raid 0. The catalog file shall contain all files on my source disks and whenever something changes, it should do incremental backup to the Raid array. 
  2. Second process is a transfer snapshots to tape process.

Now I do the following: Start the backup, write 4 TB from 2 ext. disks to Raid0. When it's filled, I start transfer to tape (2nd process).

After the data is transferred to tape (2nd process), I'd like to free all the space on the raid in order to backup the next 2 external source disks, but keep the information in the catalog file in order to do incremental backups later.

Grooming does not allow me to do this, because it wants to keep at least one backup on the raid disk, so it does not delete anything. 

 

It would be great if anyone could help me.

 

Best regards,

Andreas

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You can do incremental backups directly from Disk0 to the tape. (It's actually called "progressive" backup, not "incremental".)

 

You can't do incremental (or progressive) backup via a media set that has been emptied.

 

Why do you go via Disk 1?

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Hello Lennart, 

thank you for answering. I use Disk 1 in order to prevent performance problems with the tape drive (shoe shining). Sometimes, the data from the external drives is not provided fast enough for the tape drive. 

So it's not possible to do a progressive backup from Disk0 to Tape with a retention drive (Disk 1)?

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Hello Lennart, 

thank you for answering. I use Disk 1 in order to prevent performance problems with the tape drive (shoe shining). Sometimes, the data from the external drives is not provided fast enough for the tape drive. 

So it's not possible to do a progressive backup from Disk0 to Tape with a retention drive (Disk 1)?

Yes, it is possible as long as disk1 is large enough to hold the full backup of disk0.

 

You can continue to do full backup of half disk0 to disk1 and the progressive to tape. That will work fine, except you will put a huge load on disk0 when doing the full backup (of half the content) each time.

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You can continue to do full backup of half disk0 to disk1 and the progressive to tape. That will work fine, except you will put a huge load on disk0 when doing the full backup (of half the content) each time.

What do you mean by half disk0? 

Disk 1 (Raid0) should just be used as a buffering drive. It only has space for 2/10 external source HDDs. I just want to restore from tape and once I did a full backup of the source drives, I'd like to do incremental backups to the tape. The external HDDs are offline most of the time. 

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 I'd like to free all the space on the raid in order to backup the next 2 external source disks, 

 

 

What do you mean by half disk0? 

Disk 1 (Raid0) should just be used as a buffering drive. It only has space for 2/10 external source HDDs. I just want to restore from tape and once I did a full backup of the source drives, I'd like to do incremental backups to the tape. The external HDDs are offline most of the time. 

I probably misinterpreted what you wrote in your first post. Since Disk1 is much smaller than Disk0, I assumed you took each half of Disk0 separately.

 

Please describe in more detail about your setup. What is "external source disks" in your case, if they are neither of Disk0 or Disk1?

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Okay, I try to describe it more detailed. Just forget the terms Disk0, Disk1.

 

I have a bunch of 10 external USB 3.0 HDDs, each having 2 TB. They are plugged in separately into the backup PC that is running Retrospect 8.5 Win.

I want to backup these external drives to tape using Retrospect's D2D2T functionality, using the built in Raid 0 array as a "buffer". 

So the workflow is as follows:

  1. Plug in USB drive
  2. Progressive backup of USB drive to Raid0 (backup set 1). 
  3. Copy snapshots of "backup set 1" to tapes (backup set 2).
  4. Return to 1.

After a full backup is done, I only want to backup incrementally from USB drives to Raid0 and then copy/archive the increments from raid0 to tape. 

The only reason I use the Raid0 array in the middle is to prevent emptying the buffer of the LTO drive.

I do not need the data on it to restore, but i need the catalog file of backup set 2 with the snapshots and increments (on tape) to restore.

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Right. I thought Disk0 was ONE disk (logically).

 

You can't do it that way. In step 2, you always have a full backup, since the content of the last backup is lost.

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Okay, thank you very much for the answer. If I got it right, the disk array in the middle has to be at least as big as the sum of source drives in order to do what I plan to do, right?

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