The Short Answer is: it depends
The Longer Answer is regarding:
Would a NAS used for storing backup files be a good idea or an overkill?
In Fact, it is a commonly used practice to do so for short-Term backup
Long-Term Backups should be saved on Tapes or other medias.
what kind of NAS do I need to store what above?
The Short Answer is: it depends
The Long ...
The data you are trying to restore has a size of 500 GB, and that will not fit on a logical volume of size 24 GB. You can be more selective about what you're transferring, or you can allocate more space to the target volume group.
It sounds like the data on the logical volume you're backing up is only 19 GB. There are a few ways you can transfer that data.
To answer your question about the possibility that two drives fail at the same time: It could happen and it might be more likely than you think. I have seen it happen on a RAID5 system which then got all its data wiped.
Usually the RAID system detects that a drive has gone bad and starts rebuilding on a hot spare or manually replaced bad drive. When this ...
Reexamine what point in time you need to recover if the data is lost. Losing a week of work is bad in any organization, but may be tolerable to yours. And test restores, which is the entire point of backups.
Your current backups are good in that you have three copies of the data, and one at a different location. Assuming the weekly backups meet your business ...
The only way that you could restore your data is to use a block device that is compressed (e.g VDO, loop-device over a compressed file system like btrfs and ZFS).
However even if your data is only 17GB, the free space might contain data from previous writes and the entire LV might not be that compressible.
As compressed filesystems you can use btrfs or ZFS, ...
You can use zfs snapshot -r pool0@backup; zfs send -R pool0@backup > zfs.img to create a replicated send stream which you can restore with zfs recv.
That said, is seems similar to the issue described here
You can also try to disable deferred resilver via the zfs_resilver_disable_defer tunable.
If using a small 2-bays NAS your only option is RAID1 (obviously).
If using a 4+ bays NAS for sequential read/write workload (ie: storing files with small or no random access at all), RAID6 should be preferred due to smaller parity overhead (at 5+ bays) and better fault tolerance (any 2 disk can die without data loss). In this case, keep in mind that ...
I had the same problematic as you a couple years ago, and ultimately decided that a NAS and Raid setup wouldn't be what I need.
I decided to disregard the risk of virus and ransomwares, my house burning and most of let's say "less common" problems which may occur, and decided to only focus to protect some medias against disk failure.
And at the end,...
Can e.g. the snapshots be configured to be "copy-only" so that they
don't mess up the normal backups?
Yes, Windows Server Backup allows to choose between these two options:
VSS full backup
VSS copy backup
Choosing "VSS copy backup" should leave your SQL Server backups intact.
This tech community article explains the setting.
If you're ...
I had a look at the tar source last night and it looks like "--to-command" does create a pipe it then uses fork to run script and pipes the file data to it.
So the issue is, fork causes the forked process to inherit all the parents file descriptors which includes the /dev/nst0 device that tar has open. Tar then closes /dev/nst0 ready for media ...
Two points to address.
Creating a 24G LVM snapshot, means that the snapshot will survive 24G of changes between the original volume and the snapshot volume. The snapshot device itself will appear as if it is the same size as the original volume. Even if you never make changes to the snapshot volume, any changes to the original volume will have to recorded as ...
The concept of (un)used bytes doesn't exist on LVM's level. Whether a byte (or actually a sector) contains meaningful data or unused garbage is determined by the filesystem that lives inside the LV. The LVM doesn't know what a filesystem is. All it does is it takes a bunch of disks and combines them logically according to your instructions. It doesn't care ...