Hello Florian,
On Sun, May 17, 2015 at 6:48 AM, Florian Rist <fr...@fs.tum.de> wrote:
> Hi Ana,
> thanks for your reply.
>
You're welcome :-)
>
> > The most recent tape drives technology are LTO-6. The LTO-6 tapes
> > have a native capacity of 2.5 TB and up to 6.25 TB of compressed data.
> > Unfortunately it is really difficult to reach such amount of data in a
> > tape. Maybe a 1.5:1 compression rate depending on your data.
>
> Compression rate will be not good here, as most of the data is image and
> video data, usually already well compressed.
>
So you will need a lot of space for your full backups.
>
>
> > So you will need more than one tape for a full backup and this will
> > need
> > manual intervention for changing tapes.
>
> Yes, I know, as long as this is supported (and as far as I can see it
> is) by Bracula that's fin. I remember it was difficult using Amanda in
> 1996 or so.
>
> > If this is not a problem for you Bacula and an LTO drive is a
> > feasible solution. Otherwise you should probably think about a tape
> > library for this work.
>
> Yes, a library would be good, but I cant afford one now. Maybe I could
> get a old used library and replace the drive by a new one...
>
> > Yes, You can have full/differential/incremental backups in a
> > hard disk and then write once a week to tape. This is commonly
> > known as disk-to-disk-to-tape (D2D2T) backups.
>
> OK, in this case how much hard drive storage would I need? Enough to
> hold the full backup ore just a few TB for the weekly incremental
> backups?
>
> > What do you mean about "slow Network"? Could you be more specific?
>
> 100Mb/s and not the best topology, a few PC via VPN through 100 MBit/s
> LAN
>
I don't think this will be a problem. I had this topology a few years ago
with a standalone LTO drive. And it worked fine for a few GB being backed
up in a few nightly hours.
>
> > Are your data go across wan links? There are lots of known cases
> > with Bacula working across wan links with no problems.
>
> No WAN, I just wondered if I need to ensure a minimum data throughout
> for the LTO. I member some problems in this respect with the DDS drive.
>
I think you should do a few questions about your data.
1) How important is my data?
2) For how long should I keep a backup of them? When they will be
reclaimed? I need to keep them just for a total disaster recover? They
could be reclaimed from a year ago? From a week ago? From a month ago?
There are a lot of Bacula can do for you, but it is important to have this
previous knowledge about your data.
It is clear that you will need a full backup of about 18 TB. But will you
need 1 full backup per month? 1 full backup per week?
A simple solution could be having one full backup per month and daily
differential. In this case, you will need to keep 2 full backups and about
30 daily differential.
Your full backups could be divided into smaller ones to fill in one tape.
And you could run daily differential and full backups from different data.
This way you could use a low cost storage array and your tape drive (which
is your technology?).
Please, could you tell us what are your needs about backup retentions and
periodicity? I'm sure you will have a lot of people here to help you.
>
>
> See you
> Flo
>
>
Best regards,
Ana
>
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