* dm_mirror/dm_raid1 limitations ?.
@ 2015-01-26 13:51 Suresh Babu Kandukuru
2015-01-26 14:16 ` Heinz Mauelshagen
0 siblings, 1 reply; 5+ messages in thread
From: Suresh Babu Kandukuru @ 2015-01-26 13:51 UTC (permalink / raw)
To: dm-devel
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Use case is : Two luns are mapped from storage array to linux host which are in same SAN fabric . we want to create a mirror on the linux host with these two luns and let host use that mirror lun . basic tests suggest that dm_mirror working fine . when we have any intermittent path issues with between host and san array , host i/o just freeze , never returns back even after the path is online.
Is dm_mirror viable solution here ?. Can you point me any link which gives the limitations of dm_mirror ? . another alternate solutions you propose here ?. Thanks in advance .
Thanks
/Suresh
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* Re: dm_mirror/dm_raid1 limitations ?.
2015-01-26 13:51 dm_mirror/dm_raid1 limitations ? Suresh Babu Kandukuru
@ 2015-01-26 14:16 ` Heinz Mauelshagen
2015-01-26 15:34 ` suresh.babu.kandukuru
0 siblings, 1 reply; 5+ messages in thread
From: Heinz Mauelshagen @ 2015-01-26 14:16 UTC (permalink / raw)
To: dm-devel
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On 01/26/2015 02:51 PM, Suresh Babu Kandukuru wrote:
>
> Use case is : Two luns are mapped from storage array to linux host
> which are in same SAN fabric . we want to create a mirror on the linux
> host with these two luns and let host use that mirror lun . basic
> tests suggest that dm_mirror working fine . when we have any
> intermittent path issues with between host and san array , host i/o
> just freeze , never returns back even after the path is online.
>
Hard to tell what's happening without any kernel log.
> Is dm_mirror viable solution here ?. Can you point me any link which
> gives the limitations of dm_mirror ? . another alternate solutions you
> propose here ?. Thanks in advance .
>
We've switched the default away from "mirror" to "raid1" in order to
take advantage of th MD runtime.
Have you tested "lvcreate --type raid1 ..." yet?
Please do.
Regards,
Heinz
> Thanks
>
> /Suresh
>
>
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
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* Re: dm_mirror/dm_raid1 limitations ?.
2015-01-26 14:16 ` Heinz Mauelshagen
@ 2015-01-26 15:34 ` suresh.babu.kandukuru
2015-01-26 19:01 ` Marian Csontos
0 siblings, 1 reply; 5+ messages in thread
From: suresh.babu.kandukuru @ 2015-01-26 15:34 UTC (permalink / raw)
To: device-mapper development
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Heinzm,thanks for the quick reply.. We are using dmestup create mirror ..as we want to do that on physical San lun (block devices) ... Not the one ( lv create ) you mentioned below.. Is there any advantage going with logical volume approach lvcreate -type
/Suresh
Sent from my iPhone
> On Jan 26, 2015, at 7:46 PM, Heinz Mauelshagen <heinzm@redhat.com> wrote:
>
>
>> On 01/26/2015 02:51 PM, Suresh Babu Kandukuru wrote:
>> Use case is : Two luns are mapped from storage array to linux host which are in same SAN fabric . we want to create a mirror on the linux host with these two luns and let host use that mirror lun . basic tests suggest that dm_mirror working fine . when we have any intermittent path issues with between host and san array , host i/o just freeze , never returns back even after the path is online.
>
> Hard to tell what's happening without any kernel log.
>
>>
>> Is dm_mirror viable solution here ?. Can you point me any link which gives the limitations of dm_mirror ? . another alternate solutions you propose here ?. Thanks in advance .
>
> We've switched the default away from "mirror" to "raid1" in order to take advantage of th MD runtime.
> Have you tested "lvcreate --type raid1 ..." yet?
> Please do.
>
> Regards,
> Heinz
>
>>
>> Thanks
>> /Suresh
>>
>>
>> --
>> dm-devel mailing list
>> dm-devel@redhat.com
>> https://www.redhat.com/mailman/listinfo/dm-devel
>
> <Untitled.txt>
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* Re: dm_mirror/dm_raid1 limitations ?.
2015-01-26 15:34 ` suresh.babu.kandukuru
@ 2015-01-26 19:01 ` Marian Csontos
2015-01-28 4:03 ` Suresh Babu Kandukuru
0 siblings, 1 reply; 5+ messages in thread
From: Marian Csontos @ 2015-01-26 19:01 UTC (permalink / raw)
To: dm-devel
On 01/26/2015 04:34 PM, suresh.babu.kandukuru@oracle.com wrote:
> Heinzm,thanks for the quick reply.. We are using dmestup create
> mirror ..as we want to do that on physical San lun (block devices)
> ... Not the one ( lv create ) you mentioned below.. Is there any
> advantage going with logical volume approach lvcreate -type
One of LVM features is monitoring of mirror/raid LVs and
removing/replacing any missing legs.
Using dmsetup directly, you have to do this manually.
>
> /Suresh
>
> Sent from my iPhone
>
>> On Jan 26, 2015, at 7:46 PM, Heinz Mauelshagen <heinzm@redhat.com>
>> wrote:
>>
>>
>>> On 01/26/2015 02:51 PM, Suresh Babu Kandukuru wrote: Use case is
>>> : Two luns are mapped from storage array to linux host which are
>>> in same SAN fabric . we want to create a mirror on the linux host
>>> with these two luns and let host use that mirror lun . basic
>>> tests suggest that dm_mirror working fine . when we have any
>>> intermittent path issues with between host and san array , host
>>> i/o just freeze , never returns back even after the path is
>>> online.
>>
>> Hard to tell what's happening without any kernel log.
>>
>>>
>>> Is dm_mirror viable solution here ?. Can you point me any link
>>> which gives the limitations of dm_mirror ? . another alternate
>>> solutions you propose here ?. Thanks in advance .
>>
>> We've switched the default away from "mirror" to "raid1" in order
>> to take advantage of th MD runtime. Have you tested "lvcreate
>> --type raid1 ..." yet? Please do.
>>
>> Regards, Heinz
>>
>>>
>>> Thanks /Suresh
>>>
>>>
>>> -- dm-devel mailing list dm-devel@redhat.com
>>> https://www.redhat.com/mailman/listinfo/dm-devel
>>
>> <Untitled.txt>
>
>
>
> -- dm-devel mailing list dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: dm_mirror/dm_raid1 limitations ?.
2015-01-26 19:01 ` Marian Csontos
@ 2015-01-28 4:03 ` Suresh Babu Kandukuru
0 siblings, 0 replies; 5+ messages in thread
From: Suresh Babu Kandukuru @ 2015-01-28 4:03 UTC (permalink / raw)
To: device-mapper development
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What is difference of creating mirror with
1 ) mdadm ( mdadm --create --verbose /dev/md0 --level=mirror --raid-devices=2 /dev/sdb1 /dev/sdc1 --spare-devices=1 /dev/sdd1 )
and
2) dmsetup ( dmsetp create mirror )
Which one is better ?. and Pros and cons ?. Google is not helping much
/Suresh
-----Original Message-----
From: Marian Csontos [mailto:mcsontos@redhat.com]
Sent: Tuesday, January 27, 2015 12:32 AM
To: dm-devel@redhat.com
Subject: Re: [dm-devel] dm_mirror/dm_raid1 limitations ?.
On 01/26/2015 04:34 PM, HYPERLINK "mailto:suresh.babu.kandukuru@oracle.com" suresh.babu.kandukuru@oracle.com wrote:
> Heinzm,thanks for the quick reply.. We are using dmestup create mirror
> ..as we want to do that on physical San lun (block devices) ... Not
> the one ( lv create ) you mentioned below.. Is there any advantage
> going with logical volume approach lvcreate -type
One of LVM features is monitoring of mirror/raid LVs and removing/replacing any missing legs.
Using dmsetup directly, you have to do this manually.
>
> /Suresh
>
> Sent from my iPhone
>
>> On Jan 26, 2015, at 7:46 PM, Heinz Mauelshagen < HYPERLINK "mailto:heinzm@redhat.com" heinzm@redhat.com>
>> wrote:
>>
>>
>>> On 01/26/2015 02:51 PM, Suresh Babu Kandukuru wrote: Use case is
>>> : Two luns are mapped from storage array to linux host which are in
>>> same SAN fabric . we want to create a mirror on the linux host with
>>> these two luns and let host use that mirror lun . basic tests
>>> suggest that dm_mirror working fine . when we have any intermittent
>>> path issues with between host and san array , host i/o just freeze ,
>>> never returns back even after the path is online.
>>
>> Hard to tell what's happening without any kernel log.
>>
>>>
>>> Is dm_mirror viable solution here ?. Can you point me any link
>>> which gives the limitations of dm_mirror ? . another alternate
>>> solutions you propose here ?. Thanks in advance .
>>
>> We've switched the default away from "mirror" to "raid1" in order to
>> take advantage of th MD runtime. Have you tested "lvcreate --type
>> raid1 ..." yet? Please do.
>>
>> Regards, Heinz
>>
>>>
>>> Thanks /Suresh
>>>
>>>
>>> -- dm-devel mailing list HYPERLINK "mailto:dm-devel@redhat.com" dm-devel@redhat.com
>>> https://www.redhat.com/mailman/listinfo/dm-devel
>>
>> <Untitled.txt>
>
>
>
> -- dm-devel mailing list HYPERLINK "mailto:dm-devel@redhat.com" dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
--
dm-devel mailing list
HYPERLINK "mailto:dm-devel@redhat.com" dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel
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end of thread, other threads:[~2015-01-28 4:03 UTC | newest]
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-- links below jump to the message on this page --
2015-01-26 13:51 dm_mirror/dm_raid1 limitations ? Suresh Babu Kandukuru
2015-01-26 14:16 ` Heinz Mauelshagen
2015-01-26 15:34 ` suresh.babu.kandukuru
2015-01-26 19:01 ` Marian Csontos
2015-01-28 4:03 ` Suresh Babu Kandukuru
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