Overwritten Logical Volume Block in AIX?

We are running AIX 4.3.3 and Informix Dynamic Server Version 7.31.UC3. I am wondering if Informix writes any information over the AIX logical volume control block (LVCB) at the first 512 bytes of each logical volume. When I run the command "onstat -pP 1 0" I see the following: ****************************************************************** carsi: oncheck -pP 1 0 addr stamp nslots flag type frptr frcnt next prev 100000 1273408739 1 1000 ROOTRSV 124 3964 0 0 slot ptr len flg 1 24 108 0 slot 1: 0: 49 4e 46 4f 52 4d 49 58 2d 4f 6e 4c 69 6e 65 20 INFORMIX-OnLine 16: 43 6f 70 79 72 69 67 68 74 28 43 29 20 31 39 38 Copyright(C) 198 32: 36 2c 20 31 39 38 37 20 20 49 6e 66 6f 72 6d 69 6, 1987 Informi 48: 78 20 53 6f 66 74 77 61 72 65 2c 20 49 6e 63 2e x Software, Inc. 64: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ................ 80: 0 0 0 0 10 0 0 0 33 ba 5a a4 0 0 0 6 ........3:Z$.... 96: 0 0 0 0 0 0 0 0 37 2e 33 30 ........7.30.... ************************************************************************** ********** This looks to me like at least some of the LVCB was overwritten by Informix, if this slot exists at the beginning of the logical volume. I am coming from a Unix admin perspective and don't know much (yet) about Informix so appreciate any info. Thanks. CKG

If you are using AIX's logical volumn manager, I think that you need to use an offset for the start of the chunk. It's been a while since I've looked at this, but I think that on AIX if you do not do this, then the first set of pages will be overwritten by AIX when the system is next booted. Honda75 wrote: > We are running AIX 4.3.3 and Informix Dynamic Server Version 7.31.UC3. I am > wondering if Informix writes any information over the AIX logical volume > control block (LVCB) at the first 512 bytes of each logical volume. When I run > the command "onstat -pP 1 0" I see the following: > ****************************************************************** > carsi: oncheck -pP 1 0 > addr stamp nslots flag type frptr frcnt next > prev > 100000 1273408739 1 1000 ROOTRSV 124 3964 0 0 > slot ptr len flg > 1 24 108 0 > slot 1: > 0: 49 4e 46 4f 52 4d 49 58 2d 4f 6e 4c 69 6e 65 20 INFORMIX-OnLine > 16: 43 6f 70 79 72 69 67 68 74 28 43 29 20 31 39 38 Copyright(C) 198 > 32: 36 2c 20 31 39 38 37 20 20 49 6e 66 6f 72 6d 69 6, 1987 Informi > 48: 78 20 53 6f 66 74 77 61 72 65 2c 20 49 6e 63 2e x Software, Inc. > 64: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > ................ > 80: 0 0 0 0 10 0 0 0 33 ba 5a a4 0 0 0 6 > ........3:Z$.... > 96: 0 0 0 0 0 0 0 0 37 2e 33 30 > ........7.30.... > ************************************************************************** > ********** > This looks to me like at least some of the LVCB was overwritten by Informix, if > this slot exists at the beginning of the logical volume. I am coming from a > Unix admin perspective and don't know much (yet) about Informix so appreciate > any info. Thanks. CKG

Madison Pruet wrote: > If you are using AIX's logical volumn manager, I think that you need to use an > offset > for the start of the chunk. It's been a while since I've looked at this, but I > think that > on AIX if you do not do this, then the first set of pages will be overwritten by > AIX > when the system is next booted. > > Honda75 wrote: > > > We are running AIX 4.3.3 and Informix Dynamic Server Version 7.31.UC3. I am > > wondering if Informix writes any information over the AIX logical volume > > control block (LVCB) at the first 512 bytes of each logical volume. When I run > > the command "onstat -pP 1 0" I see the following: > > ****************************************************************** > > carsi: oncheck -pP 1 0 > > addr stamp nslots flag type frptr frcnt next > > prev > > 100000 1273408739 1 1000 ROOTRSV 124 3964 0 0 > > slot ptr len flg > > 1 24 108 0 > > slot 1: > > 0: 49 4e 46 4f 52 4d 49 58 2d 4f 6e 4c 69 6e 65 20 INFORMIX-OnLine > > 16: 43 6f 70 79 72 69 67 68 74 28 43 29 20 31 39 38 Copyright(C) 198 > > 32: 36 2c 20 31 39 38 37 20 20 49 6e 66 6f 72 6d 69 6, 1987 Informi > > 48: 78 20 53 6f 66 74 77 61 72 65 2c 20 49 6e 63 2e x Software, Inc. > > 64: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > > ................ > > 80: 0 0 0 0 10 0 0 0 33 ba 5a a4 0 0 0 6 > > ........3:Z$.... > > 96: 0 0 0 0 0 0 0 0 37 2e 33 30 > > ........7.30.... > > ************************************************************************** > > ********** > > This looks to me like at least some of the LVCB was overwritten by Informix, if > > this slot exists at the beginning of the logical volume. I am coming from a > > Unix admin perspective and don't know much (yet) about Informix so appreciate > > any info. Thanks. CKG Hi, Honda75: Yes, you are right, Informix overwrites the LVCB if you do not specify an offset for your chunk/dbspace. Therefor it is good usage to specify an offset of 1 page (4k). Madison Pruet: No, AIX does *not* overwrite the "destroyed" LVCB during reboot. AIX checks for a valid LVCB, if its overwritten it does not recreate it. The only consequence is that some LV-Informations are lost and cannot be used by LVM. Regards -- Helmut Leininger Bull AG / Vienna Open Systems Support Email: h.leininger@bull.at helmut.leininger@bull.net This opinion is mine and not necessarily that of my employer. No guarantees whatsoever.