> On Jan 4, 2021, at 5:56 PM, Gary R. Schmidt <g...@mcleod-schmidt.id.au> wrote:
>
> On 05/01/2021 07:43, Simon Gornall via Bacula-users wrote:
>> So I’ve just ordered myself a Quantum Superloader-3 LTO-8 tape drive, and
>> I’m planning on using it to back up the home network. Looking around, bacula
>> seemed to fit to a ’T’, but I thought I’d ask if what I’m planning actually
>> *does* fit well :)
>> The SL3 has 2 magazines, of 8 tapes each. I think a full backup +
>> incrementals every day will fit onto a single magazine (each is 96TB,
>> uncompressed). The main source is the 112TB NAS, which is where the Macs (5
>> of them) do their Time-Machine backups to, it holds all the movies and
>> photos for the family etc. etc. We’re only using about 50TB of the NAS at
>> the moment.
>> The plan then, is to create two pools, each of 8 volumes, and to rotate
>> backups between magazines, so it’ll do:
>> Week 1: use Pool 1
>> Sun: Full backup
>> Mon..Sat: Incr backup // Maybe split this with a
>> differential backup on Wed.
>> Week 2: use Pool 2
>> Sun: Full backup
>> Mon..Sat: Incr backup // Maybe split this with a
>> differential backup on Wed.
>> + swap tapes in Pool 1 with offsite ones
>> … and repeat, giving me a <current pool>, <previous-week pool> and <offsite
>> pool> in a way that makes it easy to just pull a magazine at a time from the
>> machine and replace it with another. Making backup-related jobs easy to do
>> is the best way I’ve found of them actually happening …
>> Looking at the docs, I think I can create a schedule with alternating weeks.
>> I was wondering if there was a better way to do it than:
>> Schedule {
>> Name = “Monthly”
>> Run = Level=Full Pool=LeftMagazine 1st|3rd|5th sun at 21:01
>> Run = Level=Incremental Pool=LeftMagazine 1st mon-sat at
>> 21:01
>> Run = Level=Full Pool=RightMagazine 2nd|4th sun at 21:01
>> Run = Level=Incremental Pool=RightMagazine 2nd mon-sat at
>> 21:01
>> }
>> It also occurs to me that you could happen to get a backup on the 5th week
>> which used the left magazine, and then switch to the first week of the next
>> month, which would again use the left magazine. I think I could work around
>> that using week-of-year maybe, but then it starts getting to be quite a long
>> config line…
>> Schedule {
>> Name = “Monthly”
>> Run = Level=Full Pool=LeftMagazine
>> w01|w03|w05|w07|w09|w11|w13|w15|w17|w19|w21|w23|w25|w27|w29|w31|w33|w35|w37|w39|w41|w43|w45|w47|w49|w51
>> sun at 21:01
>> Run = Level=Incremental Pool=LeftMagazine
>> w01|w03|w05|w07|w09|w11|w13|w15|w17|w19|w21|w23|w25|w27|w29|w31|w33|w35|w37|w39|w41|w43|w45|w47|w49|w51
>> mon-sat at 21:01
>> Run = Level=Full Pool=RightMagazine
>> w02|w04|w07|w08|w10|w12|w14|w16|w18|w20|w22|w24|w26|w28|w30|w32|w34|w36|w38|w40|w42|w44|w46|w48|w50|w52
>> sun at 21:01
>> Run = Level=Incremental Pool=RightMagazine
>> w02|w04|w07|w08|w10|w12|w14|w16|w18|w20|w22|w24|w26|w28|w30|w32|w34|w36|w38|w40|w42|w44|w46|w48|w50|w52
>> mon-sat at 21:01
>> }
>> … but that’s a bit clumsy. Is there any better way to specify alternating
>> weeks ?
>> I haven’t actually got the machine yet, so I’m just thinking about how I
>> want to set it up. Any advice much appreciated :)
> It'll probably work - but it looks to me like more trouble than its worth.
>
> I use an 8-slot single-drive auto-loader, using the
> full/differential/incremental scheme, in a software development and system
> maintenance environment.
>
> The idea behind a backup is to be able to restore files, if you pull an
> entire pool out of the loader then those files aren't available to be
> restored.
>
> To me, this is falling at the first hurdle.
Maybe I’m not being clear. My goal is to comply with the ideas behind the 3-2-1
backup method (3 copies of the data, on 2 media, 1 of which is located
off-site). *Each* of the magazines contains the entire backup - there’s no
question of files being non-local at any given time, in fact:
- The current week’s backup will be in one magazine
- The last week’s backup will be in the other magazine
- The backup from two weeks ago will be off-site.
… where by ‘backup’ I mean the full backup + a week’s worth of incrementals /
differentials.
I could do this by creating a Pool with all the Volumes (16 of them, both
magazines) and rotating the pool off-site and back, but that seems more
expensive than necessary (requiring 4 magazine), and (at least for the
foreseeable future) wasteful of space (since the backup + incrementals will fit
into one magazine)
> The idea of the tape loader is to allow you to shuffle tapes in and out as
> required, so that you don't run out of space.
I’m not expecting to run out of space. If I do (eventually) then I can buy a
fourth magazine, and I’ll have 2x the space I used to have, sacrificing the
‘last-week-backup’ and using both magazines for a single backup. See the “I
could do this by” statement above.
> Your idea basically negates this, it might be easier to just get another NAS,
> copy everything across, remove the disks, and repeat.
I respectfully disagree. I know two things about me:
1) If I use another NAS for backup (and I considered this), then inevitably I
will end up using it as primary storage. *cough* that’s what happened with the
existing NAS…
- the disks are also both delicate and heavy (not great for portability)
- and the mechanisms on the NAS for disk insertion/removal aren’t
really designed for continuous use AFAICT.
2) I know that the less work I have to do to keep a process going in the long
term, the more likely it is *to be* kept going.
- Swapping out a tape, having it rewind, whirr, and do who-knows-what
every time it is ejected from the mechanism takes time
- doing that 8 times over takes more time.
- swapping out a magazine is ‘disengage clip, pull out old, insert
new’. Takes 10 seconds.
Anyway, the machine arrives tomorrow. I can start experimenting then, I just
wanted to try and get ahead of the game. At the end of the day, bacula is
overkill for what I want (there’s one disk to back up, the NAS, which is
NFS-mounted) - but I’m not a fan of reinventing wheels, so I was hoping to be
able to use some standard software…
Cheers
Simon
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