[linux-lvm] Error setting up a mirrored lv

[linux-lvm] Error setting up a mirrored lv

[Laurenz, Dirk]

Hi,

i'm doing this:

>> hgest3301:~/LVM2.2.02.06 # lvcreate -m1 -n lvmirror -L 10G 
>> vgtest /dev/dm-55 /dev/dm-56
>>   Not enough PVs with free space available for parallel allocation.
>>   Consider --alloc anywhere if desperate.

here are the pvs?

>> hgest3301:~/LVM2.2.02.06 # pvs
>>   PV         VG          Fmt  Attr PSize   PFree
>>   /dev/dm-10 vgAGEST004  lvm2 a-    49.94G 25.94G
>>   /dev/dm-11 vgHGEST3901 lvm2 a-    49.94G     0
>>   /dev/dm-12 ehltest     lvm2 a-    25.00G 22.00G
>>   /dev/dm-13 vgtest      lvm2 a-    24.94G 24.94G
>>   /dev/dm-55 vgtest      lvm2 a-    99.94G 99.94G
>>   /dev/dm-56 vgtest      lvm2 a-    99.94G 99.94G
>>   /dev/dm-8  vgAGEST002  lvm2 a-    49.94G 45.94G
>>   /dev/dm-9  vgAGEST003  lvm2 a-    49.94G 43.94G
>>   /dev/sda8  vgOS        lvm2 a-    20.00G  3.00G
>>   /dev/sda9  vgBOTEST    lvm2 a-   111.25G 15.25G

what's wrong? 
Is there any documentation out there?
Why do we need three pvs? for a mirror?
Are there any other options?

Mit freundlichem Gruss,

Dirk Laurenz
Systems Engineer
S DE SE PS N/O
Fujitsu Siemens Computers GmbH
Hildesheimer Strasse 25
30880 Laatzen
Germany

Telephone:	+49 511 84 89 18 08
Telefax:	+49 511 84 89 25 18 08
Mobile:	+49 170 22 10 78 1 
Email:	mailto: dirk.laurenz@fujitsu-siemens.com
Internet:	http://www.fujitsu-siemens.com

RE: [linux-lvm] Error setting up a mirrored lv

[Laurenz, Dirk]

Hi,


>> -----Original Message-----
>> From: linux-lvm-bounces@redhat.com 
>> [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Laurenz, Dirk
>> Sent: Thursday, July 13, 2006 2:08 PM
>> To: LVM general discussion and development
>> Subject: [linux-lvm] Error setting up a mirrored lv
>> 
>> Hi,
>> 
>> i'm doing this:
>> 
>> >> hgest3301:~/LVM2.2.02.06 # lvcreate -m1 -n lvmirror -L 10G 
>> >> vgtest /dev/dm-55 /dev/dm-56
>> >>   Not enough PVs with free space available for parallel 
>> allocation.
>> >>   Consider --alloc anywhere if desperate.
>> 
>> here are the pvs?
>> 
>> >> hgest3301:~/LVM2.2.02.06 # pvs
>> >>   PV         VG          Fmt  Attr PSize   PFree
>> >>   /dev/dm-10 vgAGEST004  lvm2 a-    49.94G 25.94G
>> >>   /dev/dm-11 vgHGEST3901 lvm2 a-    49.94G     0
>> >>   /dev/dm-12 ehltest     lvm2 a-    25.00G 22.00G
>> >>   /dev/dm-13 vgtest      lvm2 a-    24.94G 24.94G
>> >>   /dev/dm-55 vgtest      lvm2 a-    99.94G 99.94G
>> >>   /dev/dm-56 vgtest      lvm2 a-    99.94G 99.94G
>> >>   /dev/dm-8  vgAGEST002  lvm2 a-    49.94G 45.94G
>> >>   /dev/dm-9  vgAGEST003  lvm2 a-    49.94G 43.94G
>> >>   /dev/sda8  vgOS        lvm2 a-    20.00G  3.00G
>> >>   /dev/sda9  vgBOTEST    lvm2 a-   111.25G 15.25G
>> 
what i found out was, that /dev/dm-13 was missing.
Know i have a question about the behaviour:

I have two luns from to different storage systems via dm multipath
Lets say 50 GB each. Now i want to mirror them.
Should i use dmraid or dmmirror?
How can i find out in which state the lvs are?
How does the system behave like, when a lun is missing?
If a want to switch a vg, is a vgchange -an on host a sufficient?
As u can see, there are many questions.

Mit freundlichem Gruss,

Dirk Laurenz
Systems Engineer
S DE SE PS N/O
Fujitsu Siemens Computers GmbH
Hildesheimer Strasse 25
30880 Laatzen
Germany

Telephone:	+49 511 84 89 18 08
Telefax:	+49 511 84 89 25 18 08
Mobile:	+49 170 22 10 78 1 
Email:	mailto: dirk.laurenz@fujitsu-siemens.com
Internet:	http://www.fujitsu-siemens.com

Re: [linux-lvm] Error setting up a mirrored lv

[Harik A'ttar]

Laurenz, Dirk wrote:
> Hi,
> 
> i'm doing this:
> 
>>> hgest3301:~/LVM2.2.02.06 # lvcreate -m1 -n lvmirror -L 10G 
>>> vgtest /dev/dm-55 /dev/dm-56
>>>   Not enough PVs with free space available for parallel allocation.
>>>   Consider --alloc anywhere if desperate.

> 
> what's wrong? 
> Is there any documentation out there?
> Why do we need three pvs? for a mirror?
> Are there any other options?

As you noticed, you need a log partition.  dm-mirror is a bit smarter 
then the basic MD raid1 in that it uses a log disk to keep track of 
write completions for synchronization.  I've only recently got a kernel 
that supports modern mirror, but it looks like the log file sticks at a 
single extent even with a 20gb mirror (all my free space).

Is there a reason that the mirror is on a separate volume rather then a 
serialized metadata chunk at the end of each?  Just for seektime 
performance reasons?

Re: [linux-lvm] Error setting up a mirrored lv

[Luca Berra]

On Tue, Jul 18, 2006 at 03:16:13PM -0400, Harik A'ttar wrote:
>As you noticed, you need a log partition.  dm-mirror is a bit smarter 
>then the basic MD raid1 in that it uses a log disk to keep track of 
>write completions for synchronization.  I've only recently got a kernel 
Just for fairness, modern md also supports bitmaps either on a different
device or inside the md components for this very purpose.

L.

-- 
Luca Berra -- bluca@comedia.it
        Communication Media & Services S.r.l.
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RE: [linux-lvm] Error setting up a mirrored lv

[Laurenz, Dirk]

so, what is the best way to mirror storage?

lvm ontop of multipath and mirrored lvs or
lvm ontop of md ontop of multipath

Mit freundlichem Gruss,

Dirk Laurenz
Systems Engineer
S DE SE PS N/O
Fujitsu Siemens Computers GmbH
Hildesheimer Strasse 25
30880 Laatzen
Germany

Telephone:	+49 511 84 89 18 08
Telefax:	+49 511 84 89 25 18 08
Mobile:	+49 170 22 10 78 1 
Email:	mailto: dirk.laurenz@fujitsu-siemens.com
Internet:	http://www.fujitsu-siemens.com
 

>> -----Original Message-----
>> From: linux-lvm-bounces@redhat.com 
>> [mailto:linux-lvm-bounces@redhat.com] On Behalf Of Luca Berra
>> Sent: Wednesday, July 19, 2006 12:52 AM
>> To: linux-lvm@redhat.com
>> Subject: Re: [linux-lvm] Error setting up a mirrored lv
>> 
>> On Tue, Jul 18, 2006 at 03:16:13PM -0400, Harik A'ttar wrote:
>> >As you noticed, you need a log partition.  dm-mirror is a 
>> bit smarter 
>> >then the basic MD raid1 in that it uses a log disk to keep track of 
>> >write completions for synchronization.  I've only recently 
>> got a kernel 
>> Just for fairness, modern md also supports bitmaps either on 
>> a different
>> device or inside the md components for this very purpose.
>> 
>> L.
>> 
>> -- 
>> Luca Berra -- bluca@comedia.it
>>         Communication Media & Services S.r.l.
>>  /"\
>>  \ /     ASCII RIBBON CAMPAIGN
>>   X        AGAINST HTML MAIL
>>  / \
>> 
>> _______________________________________________
>> linux-lvm mailing list
>> linux-lvm@redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-lvm
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>> 

RE: [linux-lvm] Error setting up a mirrored lv

[Denny Schierz]

[-- Attachment #1: Type: text/plain, Size: 485 bytes --]

hi,

Am Mittwoch, den 19.07.2006, 12:15 +0200 schrieb Laurenz, Dirk:
> so, what is the best way to mirror storage?
> 
> lvm ontop of multipath and mirrored lvs or
> lvm ontop of md ontop of multipath

in most cases i prefer lvm ontop of md devices, cause for better
handling and it works with every setup and distribution.

cu denny

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RE: [linux-lvm] Error setting up a mirrored lv

[Laurenz, Dirk]

Hi,

>> 
>> in most cases i prefer lvm ontop of md devices, cause for better
>> handling and it works with every setup and distribution.
>> 
does md work ontop of multipathd?=

Re: [linux-lvm] Error setting up a mirrored lv

[Kelly Sauke]

Laurenz, Dirk wrote:
> Hi,
>
>   
>>> in most cases i prefer lvm ontop of md devices, cause for better
>>> handling and it works with every setup and distribution.
>>>
>>>       
> does md work ontop of multipathd?=
>   

yes.
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>