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Disk vs File media options

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Retrospect 8.2.399

 

If I understand correctly - please verify or correct me.

 

A backup to "file" will create a single large data (.rdb) file, and a single catalog file.

 

While a backup to "Disk", will create one single catalog file, and many (600 meg?) data (.rdb) files.

 

assuming that I am correct - is there a reason to prefer one over the other when using a 3 terrabyte RAID 5-1 disk array for the backup files?

 

Thanks

 

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One thing that comes to mind (as to how I do it) is if you make backups of the media sets. With the disk media set method, you can just back up the incremental .rdb files.

 

With the "file" set, you'd have to back up the whole thing every time.

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Other differences include a file size limitation with File Media Sets (not sure how many TB that is), and the requirement that the Catalog and Data files remain together in the same directory. That precludes searching the Catalog when the actual Member is not online.

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Thanks for the answers -

 

for the first reply - Maser -

The backup storage is a RAID 5-1 (that is 2x RAID5 drives, which are then mirrored) so - I dont specifically backup the media sets.

 

for the second reply - CallMeDave -

1 - I am not sure of the limitation with Retrospect 8 (anyone?). However, with Retrospect v6, I have not exceeded the File media set size. I usually copy them off to a long term storage disk when the combined size reaches around 1TB (the capacity of a single disk drive). Then start a New File media set, leaving the old one around - that covers about 36 months.

 

2 - in v6 I can leave the catalog file around and search it to determine if an item to be recovered is actually in that specific File set. Is this capability now missing from v8?

 

 

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I backup my media sets because I had one of RAIDs lose it's volume (twice!). This hasn't happened again since June (and that was the backup set), so it may have just been a fluke, but I'd rather not lose my sets again. Eventually, I may relax about this.

 

According to the User's Guide about the size of a *file* media set:

 

...they are limited by the size of the volume on which it is stored, and also the maximum file size of the file system (FAT32, NTFS, HFS+, etc.).

 

 

And, yes, you should be able to browse the catalog if the media set is off-line.

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Retrospect 8 "disk" media sets are a completely different animal than Retrospect 6 "disk" backup sets. It's truly sad that the same name was used for both. While pointless confusion can often be caused if an old feature's name is changed for the same functionality in a new release (e.g., Retrospect 8's "rules" vs. "selectors", "media sets" vs. "backup sets" (and that term has changed several times over the life of the product), The most confusion is always caused when the same name is used for different functionality. That's what has happened with "disk" media sets (vs. "disk" backup sets and "removable disk" backup sets).

 

Probably the best synopsis I have seen is on page 6 of the "Retrospect 8 Getting Started Guide":

 

Improved Backup to Disk

 

Retrospect has always been able to backup to hard disks attached to the Retrospect server, but Retrospect 8’s disk handling abilities are greatly improved, due to the introduction of the vastly more flexible Disk Media Set. This new type of Media Set allows you to combine multiple disk volumes, including direct and network-attached hard disk drives, removable cartridge drives, and even flash media, into a single destination for your backups. You can now specify the amount of space on a disk that is allowable for use by a media set.

 

Retrospect 8 introduces disk grooming, which intelligently reclaims space on Disk Media

Sets by deleting older files and folders to make room for new ones.

You just have to do a "brain reset" and understand what Retrospect 8 disk media sets do. Part of the problem is that everyone tries to understand the underlying implementation rather than just comprehending the abstraction (now possible) that it's now just a bucket of bits into which you dump data.

 

With all of their new advantages, it's very hard for me to see any reason at all to use anything other than "disk media sets" for all backups (previously file, disk, removable disk, or optical) that aren't to tape, and it's probably worthwhile, since you have to rebuild old 6.1 catalogs anyway, to transfer those backup sets to 8.x disk media sets so that they could be groomed, could span multiple volumes, etc. Retrospect 8's disk media sets are a significant design improvement.

 

Now, none of us users have seen how "internet" backups (f/k/a/ FTP backup sets) will be implemented; we've seen some hints, but I suspect that part of the design of the disk backup sets (oops, disk media sets) is to permit a common unified format with (to be implemented, hopefully) internet backups.

 

Russ

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>You just have to do a "brain reset" and understand what Retrospect 8 disk media sets do. Part of the problem is that everyone tries to understand the underlying implementation rather than just comprehending the abstraction (now possible) that it's now just a bucket of bits into which you dump data.

 

im not sure I see that this is any different than the disk file from v6. 1 large file contains everything, and I dont care about the underlying implementation - until or unless I have to rip it apart because something failed.

 

> With all of their new advantages, it's very hard for me to see any reason at all to use anything other than "disk media sets" for all backups (previously file, disk, removable disk, or optical) that aren't to tape,

I can see 1, having to predefine a file size limit.

 

> and it's probably worthwhile, since you have to rebuild old 6.1 catalogs anyway, to transfer those backup sets to 8.x disk media sets

no I dont - they are going to stay in v6.

Just what I need - 1TB+ file being converrted. Everything "seems" ok - then I find, 10 months down the road, that it is completely F-ed.....

 

if I need to get access, Ill have a v6 system around to access them.

 

And unless Im still missing something - this doesnt address the issue/difference between "Disk" and "file" backups

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im not sure I see that this is any different than the disk file from v6. 1 large file contains everything, and I dont care about the underlying implementation - until or unless I have to rip it apart because something failed.

You might want to RTFM. Retrospect 8 disk media sets are completely different from V6. And it's not one large file in R8.

 

Russ

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