Can Linux Run Incremental Backups?
-
So when I was a Unitrends installer, one thing that I learned is that, as a rule, Linux systems can't run incrementals. Let me define just to clear up what I mean.
Full/Master - Backs up the entire system
Incremental - Backup of the changes made since the last backup, be that full/master, incremental, or differential
Differential - Backup of the changes made since the last full/master, regardless of what the most recent backup isSo the product I am learning has a built-in backup solution, and it's a Linux-based system. It's a proprietary version of Linux but still. From what I've been told, it backs up the system config primarily, and it does it in a differential means. From what I could see, it never appears to run new masters, but is just continuous differentials. If this is incrementals, it's not as bad, although you should run new masters every now and then. But again, all incrementals I've ever seen are on Windows-based systems using VSS to track changes. That's why Linux uses differentials.
I am likely missing info I need, but I just want confirmation from others about what they know. Can Linux run incrementals? I'm not talking at a VM level, but at a physical level.
Thanks,
A.J. -
@thanksaj said:
But again, all incrementals I've ever seen are on Windows-based systems using VSS to track changes. That's why Linux uses differentials.
I don't follow this statement.
-
@thanksaj said:
I am likely missing info I need, but I just want confirmation from others about what they know. Can Linux run incrementals? I'm not talking at a VM level, but at a physical level.
Of course. The ability to run an incremental and a differential come from the same mechanism.
-
The ability to take backups is not something provided by operating systems. I'm not sure what you are picturing. Neither Windows nor Linux does or does not support any particular type of backup. The type of backups supported is a factor only of the backup software used, not of the OS that you are backing up.
-
@scottalanmiller said:
@thanksaj said:
But again, all incrementals I've ever seen are on Windows-based systems using VSS to track changes. That's why Linux uses differentials.
I don't follow this statement.
For example, Unitrends can't run incrementals on a Linux system. Unitrends is able to run incrementals on Windows (and VMware but not going there atm but it's for a similar reason) because of VSS tracking changes on the system. AFAIK, Linux does not have anything like VSS that tracks changes, thus differentials are the only option.
-
@scottalanmiller said:
The ability to take backups is not something provided by operating systems. I'm not sure what you are picturing. Neither Windows nor Linux does or does not support any particular type of backup. The type of backups supported is a factor only of the backup software used, not of the OS that you are backing up.
All backup solutions, as a rule, seem to have the same abilities and limitations, due to the OSes.
-
@thanksaj said:
From what I could see, it never appears to run new masters, but is just continuous differentials. If this is incrementals, it's not as bad, although you should run new masters every now and then.
Other way around. If you take one master and then only ever take something else, that something else needs to be a differential. You want no more than two components needed for a restore. In this example, that would be the master and the latest differential.
To restore an incremental would mean that you need the master and every single incremental backup taken since the last master. If you do that over a period of a week, that is annoying and a little risk. But most companies are willing to consider that risk. If you are doing that over months or years, that's an impossible situation. You can't need to fetch hundreds of backups AND trust that every single one of them is flawless. That would be effectively impossible to restore.
-
@thanksaj said:
For example, Unitrends can't run incrementals on a Linux system. Unitrends is able to run incrementals on Windows (and VMware but not going there atm but it's for a similar reason) because of VSS tracking changes on the system. AFAIK, Linux does not have anything like VSS that tracks changes, thus differentials are the only option.
VSS is a copy of a Linux feature. LVM and BtrFS are two core means of doing system images like VSS. But you don't need either on Linux. Linux was doing differential and incremental backups a decade before VSS existed and without LVM.
Symantec BackupExec and Netbackup both do incremental on all UNIX.
-
@thanksaj said:
All backup solutions, as a rule, seem to have the same abilities and limitations, due to the OSes.
I'm not aware of any differences between them. What examples do you have?
-
@scottalanmiller said:
@thanksaj said:
From what I could see, it never appears to run new masters, but is just continuous differentials. If this is incrementals, it's not as bad, although you should run new masters every now and then.
Other way around. If you take one master and then only ever take something else, that something else needs to be a differential. You want no more than two components needed for a restore. In this example, that would be the master and the latest differential.
To restore an incremental would mean that you need the master and every single incremental backup taken since the last master. If you do that over a period of a week, that is annoying and a little risk. But most companies are willing to consider that risk. If you are doing that over months or years, that's an impossible situation. You can't need to fetch hundreds of backups AND trust that every single one of them is flawless. That would be effectively impossible to restore.
While I agree that doing it that way makes sense for the reason of data loss, for efficiency of the backups, it's INCREDIBLY inefficient. Running a new full/master at least, oh, once a month, would make sense. Then run your differentials off that.
-
@thanksaj said:
For example, Unitrends can't run incrementals on a Linux system.
It sure can. It would be pretty crazy if it didn't.
http://support.unitrends.com/ikm/questions.php?questionid=494
-
@scottalanmiller said:
@thanksaj said:
All backup solutions, as a rule, seem to have the same abilities and limitations, due to the OSes.
I'm not aware of any differences between them. What examples do you have?
I can't give brand names off the top of my head, but, perfect example, I've never seen a system that can run Incremental Forever on a Linux system. However, all backup solutions that I've seen that have that option CAN and DO run it on Windows systems, as one example. I haven't been an installer for 7 months now, but when I was, everything I was told was that incrementals were not even possible on Linux. I never worked with any Unix systems when I was doing installs, so I can't comment on that. But if you create a backup schedule on a Untirends device of a Linux system, Fulls w/ Incrementals is not even an option.
-
@scottalanmiller said:
@thanksaj said:
For example, Unitrends can't run incrementals on a Linux system.
It sure can. It would be pretty crazy if it didn't.
http://support.unitrends.com/ikm/questions.php?questionid=494
I've never seen it on any of the Linux systems I touched.
-
@thanksaj said:
While I agree that doing it that way makes sense for the reason of data loss, for efficiency of the backups, it's INCREDIBLY inefficient. Running a new full/master at least, oh, once a month, would make sense. Then run your differentials off that.
It's really not inefficient most of the time. Not sure why you think so. Doing that with incremental is only an option if all of your backups exist on a single, high reliability array (like a Unitrends appliance doing Incremental Forever.) In normal GFS tape backup rotation, doing any amount of incrementals is absolutely insane. It's no different than not having backups at all.
What about doing regular diffs makes you uncomfortable? That IS the industry standard practice, you understand. Not that "everyone does it and that makes it right." Of course some industry practices are poor. But I am not aware of there being any dispute on the differential approach being the most widely applicable concept.
-
@thanksaj said:
I've never seen it on any of the Linux systems I touched.
Why would the above statement ever lead you to believe that it didn't support it?
-
@thanksaj said:
I can't give brand names off the top of my head, but, perfect example, I've never seen a system that can run Incremental Forever on a Linux system.
You are using a single product example, that we already established is incorrect, as the only example as to why something else is true? Do you see the failed chain of reasoning here?
My car can't make it out of the garage. Therefore trucks don't drive on roads.
-
@scottalanmiller said:
@thanksaj said:
While I agree that doing it that way makes sense for the reason of data loss, for efficiency of the backups, it's INCREDIBLY inefficient. Running a new full/master at least, oh, once a month, would make sense. Then run your differentials off that.
It's really not inefficient most of the time. Not sure why you think so. Doing that with incremental is only an option if all of your backups exist on a single, high reliability array (like a Unitrends appliance doing Incremental Forever.) In normal GFS tape backup rotation, doing any amount of incrementals is absolutely insane. It's no different than not having backups at all.
What about doing regular diffs makes you uncomfortable? That IS the industry standard practice, you understand. Not that "everyone does it and that makes it right." Of course some industry practices are poor. But I am not aware of there being any dispute on the differential approach being the most widely applicable concept.
Incrementals are much smaller and faster. Differentials tend to be much larger backups. I get why you say what you do, but it all comes down to how much change happens in what span of time, and your backup method. Using tape or have few changes overall? Diffs make sense. Have a large amount of changes (like a large file server) or are using disk? Incrementals are more efficient.
-
@scottalanmiller said:
@thanksaj said:
I've never seen it on any of the Linux systems I touched.
Why would the above statement ever lead you to believe that it didn't support it?
That's also what I was always told.
-
@thanksaj said:
@scottalanmiller said:
@thanksaj said:
I've never seen it on any of the Linux systems I touched.
Why would the above statement ever lead you to believe that it didn't support it?
That's also what I was always told.
Or is it what you always believed?
-
@scottalanmiller said:
@thanksaj said:
I can't give brand names off the top of my head, but, perfect example, I've never seen a system that can run Incremental Forever on a Linux system.
You are using a single product example, that we already established is incorrect, as the only example as to why something else is true? Do you see the failed chain of reasoning here?
My car can't make it out of the garage. Therefore trucks don't drive on roads.
I can't think of the specific name but I've seen the same thing on other backup appliances I've looked at.
