AOE

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AOE

James Harper
If anyone is wanting to experiment with SAN technology, but finding
iSCSI too fiddly, have a look at AOE (ATA over Ethernet). There is a
software AoE server, and the kernel client is already in 2.6.11.

I use AOE root on dom0, and on the block devices exported to the other
domains (eg dom0 exports AOE devices, the other domains don't do AOE
themselves). This allows for domain migration to work nicely.

Have a look at: http://aoetools.sourceforge.net/ (tools + software
server)
And: http://www.coraid.com/ (hardware AOE server)

I can post some details for getting Debian root on AOE if anyone is
interested.

James

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Re: AOE

Keir Fraser

On 22 May 2005, at 05:51, James Harper wrote:

> If anyone is wanting to experiment with SAN technology, but finding
> iSCSI too fiddly, have a look at AOE (ATA over Ethernet). There is a
> software AoE server, and the kernel client is already in 2.6.11.
>
> I use AOE root on dom0, and on the block devices exported to the other
> domains (eg dom0 exports AOE devices, the other domains don't do AOE
> themselves). This allows for domain migration to work nicely.

I'm surprised that the protocol packets don't include an end-to-end
checksum. If the packets pass through a switch that occasionally
garbles packets then you could end up committing erroneous sectors to
disc.

On the other hand, if this is a significant problem then NFS/iscsi IP
checksumming may not save your data either, since the IP checksum is so
weak. For large volumes of data you care about the integrity of, you
probably really want an end-to-end CRC.

  -- Keir


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Re: AOE

Keir Fraser

On 22 May 2005, at 08:48, Keir Fraser wrote:

> I'm surprised that the protocol packets don't include an end-to-end
> checksum. If the packets pass through a switch that occasionally
> garbles packets then you could end up committing erroneous sectors to
> disc.
>
> On the other hand, if this is a significant problem then NFS/iscsi IP
> checksumming may not save your data either, since the IP checksum is
> so weak. For large volumes of data you care about the integrity of,
> you probably really want an end-to-end CRC.

Oops. The Ethernet CRC is end-to-end on a LAN, even if it's switched.
:-)

  -- Keir


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Re: AOE

Christian Limpach
In reply to this post by James Harper
On 5/22/05, James Harper <[hidden email]> wrote:
> If anyone is wanting to experiment with SAN technology, but finding
> iSCSI too fiddly, have a look at AOE (ATA over Ethernet). There is a
> software AoE server, and the kernel client is already in 2.6.11.
>
> I use AOE root on dom0, and on the block devices exported to the other
> domains (eg dom0 exports AOE devices, the other domains don't do AOE
> themselves). This allows for domain migration to work nicely.

Have you ever tried gnbd?  How does this compare to gnbd?  We've used
gnbd in exactly the same setup.

    christian

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RE: AOE

James Harper
In reply to this post by James Harper
I've tried nbd, and possibly enbd (can't remember if I got that working
or not). At the time I was using a server which had performed okay as
Windows 2000 Server for some time. When running Linux though, it crashed
all the time. The problem turned out to be a bad stick of memory, but by
then I'd been through a few attempts of iSCSI and nbd and had cursed
their unreliability (obviously, it turned out to be the server itself in
the end).

Assuming a working AoE server on the same L2 network, you simply need to
have an 'up' network adapter, and load the AoE module. You don't even
need a TCP/IP stack running. Apart from MAC filtering, there is no
security, so it should really be on its own Ethernet segment, or VLAN.

HTH

James

> -----Original Message-----
> From: Christian Limpach [mailto:[hidden email]]
> Sent: Sunday, 22 May 2005 18:30
> To: James Harper
> Cc: [hidden email]
> Subject: Re: [Xen-devel] AOE
>
> On 5/22/05, James Harper <[hidden email]> wrote:
> > If anyone is wanting to experiment with SAN technology, but finding
> > iSCSI too fiddly, have a look at AOE (ATA over Ethernet). There is a
> > software AoE server, and the kernel client is already in 2.6.11.
> >
> > I use AOE root on dom0, and on the block devices exported to the
other
> > domains (eg dom0 exports AOE devices, the other domains don't do AOE
> > themselves). This allows for domain migration to work nicely.
>
> Have you ever tried gnbd?  How does this compare to gnbd?  We've used
> gnbd in exactly the same setup.
>
>     christian


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