>-----Message d'origine-----
>De : Fajar A. Nugraha [mailto:fajar@xxxxxxxxx]
>Envoyé : jeudi 12 février 2009 15:03
>À : DOGUET Emmanuel
>Cc : xen-users@xxxxxxxxxxxxxxxxxxx
>Objet : Re: [Xen-users] Re: Xen Disk I/O performance vs native
>performance: Xen I/O is definitely super super super slow
>
>On Thu, Feb 12, 2009 at 8:37 PM, DOGUET Emmanuel
><Emmanuel.DOGUET@xxxxxxxx> wrote:
>>
>> Oops sorry!
>>
>> We use only phy: with LVM. PV only (Linux on domU,Linux form dom0).
>> LVM is on hardware RAID.
>
>That's better :) Now for more questions :
>What kind of test did you run? How did you determine that "domU was 2x
>slower than dom0"?
>How much memory did you assign to domU and dom0? Are other programs
>running? What were the results (how many seconds, how many MBps, etc.)
With :
- Oracle (Create table space : time to create and iostat)
and
- dd if=/dev/zero of=TEST bs=4k count=1250000 (5Gb for avoid mem cache).
New platform with :
Dom0: 4Go (Quad Core)
DomU1: 4Go 2 VCPUS
DomU2: 10Go 4 VCPUS
Trying two with only one DomU.
this problem is only with 2 platform.
Example with configuration with 2 RAID (HP ML370, 32 bits):
dom0: 5120000000 bytes (5.1 GB) copied, 139.492 seconds, 36.7 MB/s
domU 5120000000 bytes (5.1 GB) copied, 279.251 seconds, 18.3 MB/s
release : 2.6.18-53.1.21.el5xen
version : #1 SMP Wed May 7 09:10:58 EDT 2008
machine : i686
nr_cpus : 4
nr_nodes : 1
sockets_per_node : 2
cores_per_socket : 1
threads_per_core : 2
cpu_mhz : 3051
hw_caps : bfebfbff:00000000:00000000:00000080:00004400
total_memory : 4863
free_memory : 1
xen_major : 3
xen_minor : 1
xen_extra : .0-53.1.21.el5
xen_caps : xen-3.0-x86_32p
xen_pagesize : 4096
platform_params : virt_start=0xf5800000
xen_changeset : unavailable
cc_compiler : gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)
cc_compile_by : brewbuilder
cc_compile_domain : build.redhat.com
cc_compile_date : Wed May 7 08:39:04 EDT 2008
xend_config_format : 2
Example with configuration with 1 RAID (HP DL360, 64bits):
dom0: 5120000000 bytes (5.1 GB) copied, 170.3 seconds, 30.1 MB/s
domU: 5120000000 bytes (5.1 GB) copied, 666.184 seconds, 7.7 MB/s
release : 2.6.18-128.el5xen
version : #1 SMP Wed Dec 17 12:01:40 EST 2008
machine : x86_64
nr_cpus : 8
nr_nodes : 1
sockets_per_node : 2
cores_per_socket : 4
threads_per_core : 1
cpu_mhz : 2666
hw_caps :
bfebfbff:20000800:00000000:00000140:000ce3bd:00000000:00000001
total_memory : 18429
free_memory : 0
node_to_cpu : node0:0-7
xen_major : 3
xen_minor : 1
xen_extra : .2-128.el5
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p
xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : unavailable
cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-44)
cc_compile_by : mockbuild
cc_compile_domain : redhat.com
cc_compile_date : Wed Dec 17 11:37:15 EST 2008
xend_config_format : 2
PS: I don't use virt-install but generate myself the xmdomain.cfg. So PV or
HVM????
Bye bye.
>
>I've had good results so far, with domU's disk I/O performance is
>similar or equal to dom0. A simple
>
>time dd if=/dev/zero of=test1G bs=1M count=1024
>
>took about 5 seconds and give me about 200 MB/s on idle dom0 and domU.
>This is on IBM, hardware RAID, 7x144GB RAID5 + 1 hot spare 2.5" SAS
>disk. Both dom0 and domU has 512MB memory.
>
>>
>> For the RAID my question was (I'm bad in English):
>>
>> It's better to have :
>>
>> *case 1*
>> Dom0 and DomU on hard-drive 1 (with HP raid: c0d0)
>>
>> Or
>>
>> *case 2*
>> Dom0 on hard-drive 1 (if HP raid: c0d0)
>> DomU on hard-drive 2 (if HP raid: c0d1)
>>
>>
>
>Depending on how you use it, it might not matter :)
>General rule-of-thumb, more disks should provide higher I/O throughput
>when setup properly. In general (like when all disks are the same, for
>general-purpose domUs) I'd simply put all available disks in a RAID5
>(or multiple RAID5s for lots of disks) and put them all in a single
>VG.
>
>Regards,
>
>Fajar
>
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