Can Linux Run Incremental Backups?
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@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.
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@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?
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@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.
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@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.
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@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.
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@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?
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@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.
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@IRJ said:
@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?
It's what I was told. I don't remember who though.
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@thanksaj said:
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.
Unitrends own documents from far more than 17 months ago, let alone 7, mention how Linux is the ONLY platform on which incremental forever is available. All other platforms, like Windows, only offer it on certain versions. Linux isn't just supported, it is the most supported.
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@scottalanmiller said:
@thanksaj said:
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.
Unitrends own documents from far more than 17 months ago, let alone 7, mention how Linux is the ONLY platform on which incremental forever is available. All other platforms, like Windows, only offer it on certain versions. Linux isn't just supported, it is the most supported.
I was misinformed then.
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@thanksaj said:
I can't think of the specific name but I've seen the same thing on other backup appliances I've looked at.
I think that that is safe to assume was a misconception, as it was on Unitrends. Every enterprise backup appliance had that feature in the 1990s. Hard to believe anyone would be lacking it today.
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@thanksaj said:
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.
Incrementals are typically trivially smaller. It is quite rare for a differential to be much larger than an incremental over an appropriate period of time (say a week.)
Incrementals are always equal or better for taking backups. But are very risky for doing restores. Remember the first rule of backups - no one cares about backups, they only care about restores. Incrementals are about making backups a little easier in exchange for a lot of restore risk. Differentials are about making backups a little harder in exchange for a lot of restore protection.
Most SMBs should just do fulls all the time and be done with it.
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@scottalanmiller said:
Most SMBs should just do fulls all the time and be done with it.
This was always my choice assuming the backups would complete in the backup window.
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@Dashrender said:
This was always my choice assuming the backups would complete in the backup window.
Exactly, you only do something other than fulls when you have to. A full is the fastest thing to restore and the safest.
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@scottalanmiller said:
@Dashrender said:
This was always my choice assuming the backups would complete in the backup window.
Exactly, you only do something other than fulls when you have to. A full is the fastest thing to restore and the safest.
Also the largest to create, retain, and archive.
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@thanksaj said:
Also the largest to create, retain, and archive.
But if it can be done in your backup window, that doesn't matter at all. And if you are working with tape, which most places are, that doesn't matter either since the archive media is the same size regardless. And if you are working with disk and you have dedupe, that's not a problem either.
I think you are working from a very specific assumption of... going to disk, not having dedupe, caring far more about backups than restores and archiving without dedupe/compression/tape. None of those are the norm.
Yes, there are cases where all fulls don't make sense. The bulk of those are services by fulls and diffs.
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And when doing a full backup to disk, if that disk media already contains the full from before it only needs to backup the diffs to make a another full. So the additional overhead of doing a full again, in the situations where you see it as being unnecessary overhead, doesn't have to have that overhead because the bulk of the data is already there.
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With Unitrends in particular, some Linux distro's do in fact support incremental backups. Some do not. Obviously it's not on the OS' side of the equation, but that's the relationship.
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@art_of_shred said:
With Unitrends in particular, some Linux distro's do in fact support incremental backups. Some do not. Obviously it's not on the OS' side of the equation, but that's the relationship.
In the KB it states that all support it. What distros have you seen that have had a problem? And do you know if it is caused by the distro or is it the setup? Obviously Unitrends has to rely on some component, like LVM or the filesystem, for the flags that they use. It seems like an odd setup would cause issues more likely than a distro in particular.
Similarly, there are ways to run Windows where it could not be handled incrementally either. But Windows is vastly more standardized than Linux, of course, so what might actually happen on Linux is pretty much unthinkable on Windows.
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I don't remember what doesn't support it, but that's true, from what I was told and what I have experienced. I can't speak for the KB article. Which article ID?
