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