Re: [BackupPC-users] Prepare for the worst, Howto backup the backuppc-se

to the question of how and why backuppc server would 'know' where the aoe disk are, aoe is actually a protocol like like IP. it is only visible on the same network, as in no routing possible, period. the aoe module in the kernel looks at the local network and can see all the local aoe nodes because they are so close** meaning they look like they are all in the same room so it is quite easy to find the guy standing next to you :)

that is the big advantage to aoe, as well as being such a low level protocal that it skips TCP/IP overhead and can give near-wire speeds. I can pull 11.7MB/s off 12.5MB/s 100Mb ethernet and 116MB/s off gigabit, which is about as good as it gets.

keep in mind that these need to be on the same physical network, not on a network across the country. if you need to get further than that, you need to use iSCSI.

iSCSI is a bit more complicated, but it is not so bad either. with iSCSI you just need to make each target have a specific name in a FQDN type format. You can put that in DNS if you like but you can also tell an initiator aka 'client' the IP address of the disk target so you dont have to mess with DNS. What is nice about iSCSI is that it is routable. and it also is using scsi packets. aoe is using ATA packets and while iscsi is using scsi packets, scsi packets being a bit more efficient in format meaning that though aoe can have a bit higher thoroughput, iscsi can do a bit better on I/O.

On Tue, Jul 22, 2008 at 1:09 PM, Kurt Tunkko <kurt.tunko AT web DOT de> wrote:

Hey Dan,

dan wrote:
> AOE is quite simple.

:-o ... wait, not THAT simple ... simple is something like: throw in
coin here -> get a beer :-)

I just think that I don't fully understand the concept of AOE and how I
can apply your setup in order to back our server to a 3rd harddrive that
is NOT in the same room like our server.

As far as I understand your idea, I would setup an other-machine that
will have one harddrive/parition configured as AOE.

BackupPC-Server -> network -> other-machine -> AOE-Disk

have I understand this right - since we have lots of spare machines
available there wouldn't be a problem setting up another one.

BUT I don't get how the backuppc-server "knows" where the AOE disk is?
sounds like magic.

If it's not to offtopic I would like to ask if you can add some more
newbie-friendly information how this is working, maybe using the names
backuppc-server (that wants to add the AOE-device to its RAID) and
aoeserver (that has the real drive built in).

thanks a lot - I'm looking forward to make some testing

- Kurt

dan wrote:
> [...] on ubuntu you can build a target like this

>
> have a spare drive/partition/lvm!
> sudo apt-get install vblade
> vblade 0 0 eth0 /dev/sdc
>
> thats it! now you are exporting a device on shelf 0, slot 0 (vblade 0 0)
>
> on another machine
> sudo apt-get install aoetools
> modprobe aoe
>
> you should now see /dev/etherd/e0.0 (this is the shelf 0, slot 0 drive
> from the other machine)
>
> done!
>
> a 'client' can see any aoe device on the network, without even having an
> IP address. IP is not used at all on aoe.
>
> now on the 'client' machine, you can
> "mkfs.ext3 /dev/etherd/e0.0 && mkdir /mnt/e0.0 && mount /dev/etherd/e0.0
> /mnt/e0.0"
>
> or better yet, add it to your raid array with mdadm.

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Re: [BackupPC-users] Prepare for the worst, Howto backup the backuppc-server