Re: [Xen-users] iscsi initiator on PV DomU problem

[Longina Przybyszewska <longina@xxxxxxxxxxxx>]

On Mon, 9 Mar 2009, Fajar A. Nugraha wrote:

> On Mon, Mar 9, 2009 at 7:56 PM, Longina Przybyszewska
> <longina@xxxxxxxxxxxx> wrote:
> > I have got 300gb iscsi target ( residence on SAN ) which should be directly
> > bound to domU.
> > (DomU: PV Ubuntu Hardy Linux 2.6.24-19-xen, Dom0: UbuntuHardy Linux
> > 2.6-24-22-xen).
> First of all, I believe you'd get better performance if the initiator
> is on dom0 instead of domU.
It seems that management could be easier if there are multiple iscsi 
targets.
My iscsi targets get their own PVM and they access it through 
bonding interface with vlan and transparent bridge on top of it - IP 
address is set first for PVM.
> > It comes up as 500gb block device!
> > ========
> > attempt to access beyond end of device
> > sda: rw=0, want=976639545, limit=629147647
> > ========
> It means domU correctly recognize the block device as 629147647
> sectors of 512-bytes long (300GB), but it was asked to get sector
> number 976639545.
>
> > cfdisk /dev/sda : "Fatal Error: Bad primary partition 0: Partition ends
> > after end-of-disk"
> >
> > cfdisk /dev/sda1 : "Disk Driver /dev/sda1, size 500,0 Gb free space"
> > Then I kan make primary  paritions assigned name /dev/sda1p1, /dev/sda1p2.
> Probably because there's already a partition table on that block
> device, and it's messed up (maybe because the block the device was
> used previously, and then shrinked).
This is probably what happened - how could be this avoided?

> What does "cat /proc/partitions" and "fdisk -l /dev/sda" shows?

cat /proc/partitions:

8       0       314573823 sda
8       1       488319741 sda1

fdisk -l /dev/sda:

Disk /dev/sda: 322.1 Gb 322123595264 bytes
255 heads, 63 sectors/track, 39162 cylinders
Units = cylinders of 16085 * 512 = 8225280 bytes
Disk identifier: 0x00000001

Device   Boot   Start   End     Blocks          Id      System
/dev/sda1        1      60783   488319741       83      Linux

> If it is indeed messed up partition table, you can use fdisk's extra
> functionality to change the number of heads, sectors/tracks, or
> cylinders.
Is it that one - "use it if you know what are you doing ?" :)
How can I find out about the target's type - 
> If it's a blank target with MBR partition, zeroing the first 512-byte
> of the disk (with dd or whatever) should erase existing partition
> table and let fdisk work out reasonable parameters. If it's GPT
> parition though things can get a little more complicated :)
How kan I find it out ?

cheers
Longina

> Regards,
>
> Fajar
>
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--
--
Longina Przybyszewska, system programmer
IT@Naturvidenskab

IMADA, Department of Mathematics and Computer Science

University of Southern Denmark, Odense
Campusvej 55,DK-5230 Odense M, Denmark

tel: +45 6550 2359 - http://www.imada.sdu.dk
email: longina@xxxxxxxxxxxx
--

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