Gentoo Archives: gentoo-user

From: Alan McKinnon <alan.mckinnon@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Backups and snapshots [Was: Organising btrfs subvolumes]
Date: Wed, 28 May 2014 11:08:40
Message-Id: 5385C385.8020007@gmail.com
In Reply to: Re: [gentoo-user] Backups and snapshots [Was: Organising btrfs subvolumes] by Joost Roeleveld
1 On 28/05/2014 11:58, Joost Roeleveld wrote:
2 > On Tuesday 27 May 2014 23:35:26 Alan McKinnon wrote:
3 >> On 27/05/2014 17:12, J. Roeleveld wrote:
4 >>> I have a yearly (full), monthly, weekly and daily. Each incremental is
5 >>> against the most recent one of itself or longer period.
6 >>> That means having to keep multiple snapshots active, which I prefer to
7 >>> avoid.
8 >>>
9 >>> But, it is a good idea for backing up desktops and laptops.
10 >>
11 >> I'm curious why you have yearly snapshots. I've yet to find any sane
12 >> production system where a yearly backup had any worth at all. Even
13 >> monthly is pushing it...
14 >>
15 >> Or do you do it to have a decent start point for incrementals?
16 >
17 > It's to have a decent start point for incrementals.
18 > Below are the 2 biggest shares on the NAS:
19 >
20 > /dev/xvda17 7.1T 5.9T 1.2T 84% /data/unsorted
21 > /dev/xvda16 3.0T 2.4T 517G 83% /data/software
22 >
23 > It is impossible to do a full backup on a daily or even weekly basis.
24 >
25 > Previously, I had 1 full backup and then a daily incremental. This appears
26 > like a good idea, untill you need to restore the filesystem from backups when
27 > the crash occured 2 years later.
28 > That is 1 full backup and over 700 incrementals....
29 >
30 > Currently, I do the following:
31 > Every year, a full backup
32 > Then, every month, I have an incremental based on either the yearly or
33 > previous monthly.
34 > Ditto for the weekly (but then based on monthly or weekly)
35 > And again for the daily.
36
37
38
39 OK, that makes sense.
40
41 It reminds me of an issue my wife had with the data warehouse when she
42 worked at the bank. In a nutshell, they needed backups but backups were
43 impossible to achieve because physics says so. They needed to get data
44 off the disk 4 times faster than data comes off a disk - SCSI limits
45 being rather hard limits :-) That opinion didn't go down well when I
46 offered it
47
48 The solution was to do it much like your plan above.
49 With the benefit that the infrequent full backups would be done on a
50 fixed schedule in a change window with X hours downtime that was known
51 well in advance.
52
53
54 --
55 Alan McKinnon
56 alan.mckinnon@×××××.com

Replies

Subject Author
Re: [gentoo-user] Backups and snapshots [Was: Organising btrfs subvolumes] Joost Roeleveld <joost@××××××××.org>