On 8/5/2020 2:16 AM, deloptes wrote:
Leslie Rhorer wrote:DAR allows for not only incremental backups, but also incremental deletions. ??I find it extremely useful, and allows for as much space saving on the live system as one likes. ??I suggest you check it out.someone should ask them to implement deduplication, because nowdays it is impossible to do meaningful backups without.
In this context what, exactly, is de-duplication? I fail to see how any meaningful interpretation of the term is salient to backups. To compression, yes, to symbolic interpretation, surely, and to saving space on a drive and reducing access times, you bet. To backups? I don't really see it, unless you mean hard-link handling, which it does most admirably. Soft links, of course, are fairly straightforward. DAR does handle sparse files exceedingly well.
May I ask what is your active disk size
What do you mean by "active" disk size? In each of my main arrays there are 8 spindles of 8 Terabytes each. Six spindles worth are encoded with flat data and 2 spindles worth with parity. RAID 6 does not assign any disks specifically for data or for parity as RAID 3 and RAID 4 do. Instead, with both RAID 5 and RAID 6, parity is distributed across every drive, and the data is also distributed across all the drives, interleaved with the parity. All put together, the available volume size is 46.9 Terabytes (43.6 Teribytes) after formatting. The main server currently has 22 Terabytes of data on it. The backup server is effectively full.
and how big is the disk size of the backup?
The individual drives vary in size. Mostly they are 3 Terabytes, but some are 2T and some are 4T. Future backups are going to be to 5T and 8T drives. It doesn't really matter. DAR does not care. For ease and simplicity, I usually format each drive into a single file system and direct DAR to use slices just under 100G. This results in no more than 100G of wasted space on any drive, and usually far less.
What kind of compression does it (DAR) support.
With my main system, it doesn't really matter, because the vast majority of the data (more than 95%) is incompressible. In general, gzip, bzip2, lzo, xz/lzma algorithms are directly supported by DAR, and DAR supports both inclusion and exclusion parameters.