Re: RES: [Xen-users] SAN + XEN + FC + LVM question(s)

[Wendell Dingus <wendell@xxxxxxxxxxxxx>]

Another concern I've had is disk performance. I figure virtualization has to affect it at least some, just how much though?

Here's some test results from bonnie++
http://216.184.67.226/xen.html

dom0 - Dual core 1.8Ghz Intel CPU, 4GB RAM, SATA 160GB Drive
file - a VM installed into a file in dom0, limited to 512MB of RAM and 1 VCPU
file2 - Same as above but with 2 VCPUs and 1GB RAM
lv - a VM installed into an LV with same restrictions as "file"
lv2 - same as LV but with 2 VCPUs and 1GB RAM

In all cases above the OS installed is CentOS 5.2 x86_64 and only pointy-clicky admin tools were accessed (virt-manager, system-config-lvm).

00:1f.2 RAID bus controller: Intel Corporation 82801 SATA RAID Controller (rev 02)
    Subsystem: Dell Unknown device 0238
    Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 20
    I/O ports at f800 [size=8]
    I/O ports at f700 [size=4]
    I/O ports at f600 [size=8]
    I/O ports at f500 [size=4]
    I/O ports at f400 [size=32]
    Memory at fdffc000 (32-bit, non-prefetchable) [size=2K]
    Capabilities: [80] Message Signalled Interrupts: 64bit- Queue=0/4 Enable-
    Capabilities: [70] Power Management version 3
    Capabilities: [a8] #12 [0010]
    Capabilities: [b0] Vendor Specific Information

# lsmod | grep libata
libata                192217  1 ahci
scsi_mod              188793  8 ib_iser,iscsi_tcp,libiscsi,scsi_transport_iscsi,sr_mod,sg,libata,sd_mod



----- "Pasi KÃrkkÃinen" <pasik@xxxxxx> wrote:
> On Tue, Sep 16, 2008 at 07:49:16AM -0500, Javier Guerra Giraldez wrote:
> > On Monday 15 September 2008, Bruno Bertechini wrote:
> > > Just complementing Javier's email, I have tested the "online" resizing
> > > inside domU's. It does not work without reboot or (re)-mount the drive /
> > > partition.
> >
> > it would be interesting to know where in the chain
> > (xend-xenbus-pvdrivers-block device) is the resize getting stuck.  ideally,
> > partscan _should_ get the new size, and if you do use 'inner' LVM, pvresize
> > _should_ do the trick too.
> >
> > does anybody knows enough about this? who should we be nagging to fix it?
> >
>
> There's no way in Xen to resize domU VBD devices on the fly..
>
> See recent discussion about this on xen-devel:
> http://lists.xensource.com/archives/html/xen-devel/2008-09/msg00158.html
>
> -- Pasi
>

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