mirroring dbspaces

Hi all, anyone having experience with mirroring ? I inherited an informix config from a former collegue, and it looks very strange and insecure to me. In short : system running Solaris 8, 2 disks. All slices EXCEPT slice 6 (used for Informix raw-devices), are mirrored with Solstice Diskuite. In slice 6 there are 2 instances, first instance starts at offset 0, second instance starts at offset 6000000 (2K-pages). Both instances have the MIRROR parameter set to 1 in the onconfig-file. First instance only has root dbspace mirrored. Second instance does not have any mirrored dbspace. Pretty insecure in my opinion. So I read about mirroring in the administration guide and I found how to mirror the dbspaces but I'm concerned about the second instance which does not have the root dbspace already mirrored. Is it a MUST to mirror the root dbspace during INITIALISATION ? Or (as the parameter MIRROR is set to 1) can I just add a mirror for this root dbspace just as for an other dbspace ? Or should I use an alternative solution : removing the mirror of root dbspace for instance 1 (the only space occupied in slice 6 of mirror disk) and mirror slice 6 also with Solstice Disksuite ? (In this case I have to change the links for the raw-devices of course) Any recommendations ? Thanks, Jacques Lapeire

Jacques Received wisdom has always been that it is better (more efficient and quicker and flexible) to use O/S or hardware mirroring rather than Informix. However further advice has been to always set mirroring on dbapaces 1 (yes) so it can be used if required without reinitialising the engine. No you need not reinitialise the engine to mirror the root dbspace provided morroring was set to ! at original initialisation, however, IMHO, this should only be considered as an emergency fix and mirroring using disk suite is far better. Keith -> -----Original Message----- -> From: JACQUES LAPEIRE [mailto:jacques.lapeire@siemens.com] -> Sent: Monday, August 21, 2006 12:15 PM -> To: ids@iiug.org -> Subject: mirroring dbspaces [7309] -> -> Hi all, -> -> anyone having experience with mirroring ? -> -> I inherited an informix config from a former collegue, and -> it looks very -> strange and insecure to me. -> -> In short : system running Solaris 8, 2 disks. -> All slices EXCEPT slice 6 (used for Informix raw-devices), -> are mirrored with -> Solstice Diskuite. -> In slice 6 there are 2 instances, first instance starts at offset 0, -> second instance starts at offset 6000000 (2K-pages). -> -> Both instances have the MIRROR parameter set to 1 in the -> onconfig-file. -> -> First instance only has root dbspace mirrored. -> Second instance does not have any mirrored dbspace. -> -> Pretty insecure in my opinion. -> -> So I read about mirroring in the administration guide and I -> found how to -> mirror the dbspaces but I'm concerned about the second -> instance which does not -> have the root dbspace already mirrored. -> Is it a MUST to mirror the root dbspace during INITIALISATION ? -> Or (as the parameter MIRROR is set to 1) can I just add a -> mirror for this root -> dbspace just as for an other dbspace ? -> -> Or should I use an alternative solution : removing the -> mirror of root dbspace -> for instance 1 (the only space occupied in slice 6 of mirror -> disk) and mirror -> slice 6 also with Solstice Disksuite ? (In this case I have -> to change the -> links for the raw-devices of course) -> -> Any recommendations ? -> -> Thanks, -> Jacques Lapeire -> -> -> ************************************************************* -> ****************** -> Forum Note: Use "Reply" to post a response in the -> discussion forum. -> ******************************************************************************** *************** This email, including any attachment, is confidential and may be legally privileged. If you are not the intended recipient or if you have received this email in error, please inform the sender immediately by reply and delete all copies from your system. Do not retain, copy, disclose, distribute or otherwise use any of its contents. Whilst we have taken reasonable precautions to ensure that this email has been swept for computer viruses, we cannot guarantee that this email does not contain such material and we therefore advise you to carry out your own virus checks. We do not accept liability for any damage or losses sustained as a result of such material. Please note that incoming and outgoing email communications passing through our IT systems may be monitored and/or intercepted by us solely to determine whether the content is business related and compliant with company standards. ******************************************************************************** ***************

The way it was explained to me when I was working at Informix in the late 1990's was that you should mirror the critical dbspaces (root, physical log and, if disk space was available, the logical logs). Your gain was in the way Informix does it reads: it would perform reads using the mirror while performing writes to the original dbspace. Have things changed ... or was I improperly educated? Take care. Clifton -----Original Message----- From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Simmons, Keith Sent: Monday, August 21, 2006 6:36 AM To: ids@iiug.org Subject: RE: mirroring dbspaces [7310] Jacques Received wisdom has always been that it is better (more efficient and quicker and flexible) to use O/S or hardware mirroring rather than Informix. However further advice has been to always set mirroring on dbapaces 1 (yes) so it can be used if required without reinitialising the engine. No you need not reinitialise the engine to mirror the root dbspace provided morroring was set to ! at original initialisation, however, IMHO, this should only be considered as an emergency fix and mirroring using disk suite is far better. Keith -> -----Original Message----- -> From: JACQUES LAPEIRE [mailto:jacques.lapeire@siemens.com] -> Sent: Monday, August 21, 2006 12:15 PM -> To: ids@iiug.org -> Subject: mirroring dbspaces [7309] -> -> Hi all, -> -> anyone having experience with mirroring ? -> -> I inherited an informix config from a former collegue, and -> it looks very -> strange and insecure to me. -> -> In short : system running Solaris 8, 2 disks. -> All slices EXCEPT slice 6 (used for Informix raw-devices), -> are mirrored with -> Solstice Diskuite. -> In slice 6 there are 2 instances, first instance starts at offset 0, -> second instance starts at offset 6000000 (2K-pages). -> -> Both instances have the MIRROR parameter set to 1 in the -> onconfig-file. -> -> First instance only has root dbspace mirrored. -> Second instance does not have any mirrored dbspace. -> -> Pretty insecure in my opinion. -> -> So I read about mirroring in the administration guide and I -> found how to -> mirror the dbspaces but I'm concerned about the second -> instance which does not -> have the root dbspace already mirrored. -> Is it a MUST to mirror the root dbspace during INITIALISATION ? -> Or (as the parameter MIRROR is set to 1) can I just add a -> mirror for this root -> dbspace just as for an other dbspace ? -> -> Or should I use an alternative solution : removing the -> mirror of root dbspace -> for instance 1 (the only space occupied in slice 6 of mirror -> disk) and mirror -> slice 6 also with Solstice Disksuite ? (In this case I have -> to change the -> links for the raw-devices of course) -> -> Any recommendations ? -> -> Thanks, -> Jacques Lapeire -> -> -> ************************************************************* -> ****************** -> Forum Note: Use "Reply" to post a response in the -> discussion forum. -> **************************************************************************** ******************* This email, including any attachment, is confidential and may be legally privileged. If you are not the intended recipient or if you have received this email in error, please inform the sender immediately by reply and delete all copies from your system. Do not retain, copy, disclose, distribute or otherwise use any of its contents. Whilst we have taken reasonable precautions to ensure that this email has been swept for computer viruses, we cannot guarantee that this email does not contain such material and we therefore advise you to carry out your own virus checks. We do not accept liability for any damage or losses sustained as a result of such material. Please note that incoming and outgoing email communications passing through our IT systems may be monitored and/or intercepted by us solely to determine whether the content is business related and compliant with company standards. **************************************************************************** ******************* **************************************************************************** *** Forum Note: Use "Reply" to post a response in the discussion forum.

Clifton, You are correct about the advantages of mirroring, however, almost all mirror (RAID1) system, hardware and software, also read from one drive of the pair while reading or writing from/to the other. There is sometimes a slight advantage in using Informix mirroring because the engine knows that it can read in parallel, but in tests that Informix did years ago Informix mirroring was in a dead head with OS level mirrors and slower than firmware or hardware based mirroring systems. I haven't tested it lately but I can only assume that this relationship still holds. Art S. Kagel ----- Original Message ----- From: Clifton Bean <ids@iiug.org> At: 8/21 8:25:29 The way it was explained to me when I was working at Informix in the late 1990's was that you should mirror the critical dbspaces (root, physical log and, if disk space was available, the logical logs). Your gain was in the way Informix does it reads: it would perform reads using the mirror while performing writes to the original dbspace. Have things changed ... or was I improperly educated? Take care. Clifton -----Original Message----- From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Simmons, Keith Sent: Monday, August 21, 2006 6:36 AM To: ids@iiug.org Subject: RE: mirroring dbspaces [7310] Jacques Received wisdom has always been that it is better (more efficient and quicker and flexible) to use O/S or hardware mirroring rather than Informix. However further advice has been to always set mirroring on dbapaces 1 (yes) so it can be used if required without reinitialising the engine. No you need not reinitialise the engine to mirror the root dbspace provided morroring was set to ! at original initialisation, however, IMHO, this should only be considered as an emergency fix and mirroring using disk suite is far better. Keith -> -----Original Message----- -> From: JACQUES LAPEIRE [mailto:jacques.lapeire@siemens.com] -> Sent: Monday, August 21, 2006 12:15 PM -> To: ids@iiug.org -> Subject: mirroring dbspaces [7309] -> -> Hi all, -> -> anyone having experience with mirroring ? -> -> I inherited an informix config from a former collegue, and -> it looks very -> strange and insecure to me. -> -> In short : system running Solaris 8, 2 disks. -> All slices EXCEPT slice 6 (used for Informix raw-devices), -> are mirrored with -> Solstice Diskuite. -> In slice 6 there are 2 instances, first instance starts at offset 0, -> second instance starts at offset 6000000 (2K-pages). -> -> Both instances have the MIRROR parameter set to 1 in the -> onconfig-file. -> -> First instance only has root dbspace mirrored. -> Second instance does not have any mirrored dbspace. -> -> Pretty insecure in my opinion. -> -> So I read about mirroring in the administration guide and I -> found how to -> mirror the dbspaces but I'm concerned about the second -> instance which does not -> have the root dbspace already mirrored. -> Is it a MUST to mirror the root dbspace during INITIALISATION ? -> Or (as the parameter MIRROR is set to 1) can I just add a -> mirror for this root -> dbspace just as for an other dbspace ? -> -> Or should I use an alternative solution : removing the -> mirror of root dbspace -> for instance 1 (the only space occupied in slice 6 of mirror -> disk) and mirror -> slice 6 also with Solstice Disksuite ? (In this case I have -> to change the -> links for the raw-devices of course) -> -> Any recommendations ? -> -> Thanks, -> Jacques Lapeire -> -> -> ************************************************************* -> ****************** -> Forum Note: Use "Reply" to post a response in the -> discussion forum. -> **************************************************************************** ******************* This email, including any attachment, is confidential and may be legally privileged. If you are not the intended recipient or if you have received this email in error, please inform the sender immediately by reply and delete all copies from your system. Do not retain, copy, disclose, distribute or otherwise use any of its contents. Whilst we have taken reasonable precautions to ensure that this email has been swept for computer viruses, we cannot guarantee that this email does not contain such material and we therefore advise you to carry out your own virus checks. We do not accept liability for any damage or losses sustained as a result of such material. Please note that incoming and outgoing email communications passing through our IT systems may be monitored and/or intercepted by us solely to determine whether the content is business related and compliant with company standards. **************************************************************************** ******************* **************************************************************************** *** Forum Note: Use "Reply" to post a response in the discussion forum. ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum.