replication tecnologies and blobspaces
User asked which replication technologies (HDR, SDS, RSS) support blobspaces. Experts clarified: HDR/SDS/RSS don't replicate dumb blobs (BYTE/TEXT) in blobspaces because logical logs don't track blobspace page changes—only in-table blobs work. However, smart blobs (BLOB/CLOB) in logged smartblobspaces do replicate. ER supports all blob types. Backup/restore is safe because archives contain blob before/after images.
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Someone knows wich replication tecnologies (HDR, SDS, RSS, CL) have problems with blobspaces? I'm reading in some IBM pages that HDR does not work but I'm afraid of missing information. Informix versión 11.70 and 12.10 If all replications are based in logical logs, if it fails on one because of logical logs not aplying in blobspaces(HDR) shoudn't in fail in all? https://www.ibm.com/support/knowledgecenter/SSGU8G_12.1.0/com.ibm.admin.doc/ids_ admin_0920.htm As always, thanks a lot in advance!
HDR, RSS, & SDS do not support blobspace dumb blobs (types BYTE and TEXT). Dumb blobs are only replicated if they are stored IN TABLE. This is because the logical logs do not contain modified blobspace pages only a note that page XXX has been replaced by page YYY. Rollback of blobspace blob changes is accomplished by not deleting page XXX until the next archive is complete. However, ER does support blobspace dumb blobs. The ER threads that send out modified data DO copy the blobspace pages when appropriate. As for smartblob types (BLOB & CLOB), they replicate under HDR/RSS/SDS if the smart blobspace is a logged space. By default smart blobspaces are logged but you can mark them as unlogged. For example you ouwld want temp smart blobspaces to be unlogged. Art Art S. Kagel, President and Principal Consultant ASK Database Management www.askdbmgt.com Blog: http://informix-myview.blogspot.com/ Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Thu, Sep 1, 2016 at 7:28 AM, JACOBO BALBUENA <jacobo.bc@gmail.com> wrote: > Someone knows wich replication tecnologies (HDR, SDS, RSS, CL) have > problems > with blobspaces? I'm reading in some IBM pages that HDR does not work but > I'm > afraid of missing information. > Informix versión 11.70 and 12.10 > > If all replications are based in logical logs, if it fails on one because > of > logical logs not aplying in blobspaces(HDR) shoudn't in fail in all? > > > https://www.ibm.com/support/knowledgecenter/SSGU8G_12.1.0/ > com.ibm.admin.doc/ids_admin_0920.htm > > As always, thanks a lot in advance! > > > ************************************************************ > ******************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --001a1146fb7e3afb8a053b7111be
Hi,
there are multiple possibilities to store binary data in Informix and each one
has a different way to establish a replication:
1) use a byte column in Table Space -> works with HDR (when database has
logging)
-> this is rarely used because byte columns in a standard table space do
consume significantly more space
2) use a byte column in a blob space -> does not work with HDR
-> there is no way to do this, because the byte activity in a blobspace is not
logged the same way as standard transactions.
3) use a blob column (with a smartblob space) -> works, when the smartblob is
set to logging (either on creation or later when establishing the HDR,
onspaces -ch is the command to use)-> check if logging is active before doing a Level 0 backup to prepare for HDR.
There are other ways to set up replication (RSS), but I think the same
restrictions apply.
Marcus Haarmann
----- Ursprüngliche Mail -----
Von: "JACOBO BALBUENA" <jacobo.bc@gmail.com>
An: ids@iiug.org
Gesendet: Donnerstag, 1. September 2016 13:28:35
Betreff: replication tecnologies and blobspaces [37717]
Someone knows wich replication tecnologies (HDR, SDS, RSS, CL) have problems
with blobspaces? I'm reading in some IBM pages that HDR does not work but I'm
afraid of missing information.
Informix versión 11.70 and 12.10
If all replications are based in logical logs, if it fails on one because of
logical logs not aplying in blobspaces(HDR) shoudn't in fail in all?
https://www.ibm.com/support/knowledgecenter/SSGU8G_12.1.0/com.ibm.admin.doc/ids_
admin_0920.htm
As always, thanks a lot in advance!
*******************************************************************************
Forum Note: Use "Reply" to post a response in the discussion forum.
Thanks all for help.
Thanks Art. A side question about what you said "logical logs do not contain modified blobspace pages ". Is there any backup/restore weird behaviour with Byte and Text data because of that? For example, any kind of situation where I would loose more data if I try a restore from backup on those kind of data type?
No. Your data is safe. The archives always contain the blobspace data which
includes both the before image and the after image of the blobs that were
modified since the last archive. The pre-images are needed in the archive
in case you want to perform a point-in-time restore using onbar to a point
before the blob was modified and they are needed until the transaction is
committed in case of a rollback or fast recovery after a crash. Those "old"
images are deleted at the end of the archive since they are no longer
needed.
Art
Art S. Kagel, President and Principal Consultant
ASK Database Management
www.askdbmgt.com
Blog: http://informix-myview.blogspot.com/
Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on the IIUG, nor any other organization with which I am
associated either explicitly, implicitly, or by inference. Neither do
those opinions reflect those of other individuals affiliated with any
entity with which I am affiliated nor those of the entities themselves.
On Thu, Sep 1, 2016 at 9:42 AM, JACOBO BALBUENA <jacobo.bc@gmail.com> wrote:
> Thanks Art.
> A side question about what you said "logical logs do not contain modified
> blobspace pages ".
> Is there any backup/restore weird behaviour with Byte and Text data
> because of
> that? For example, any kind of situation where I would loose more data if I
> try a restore from backup on those kind of data type?
>
>
> ************************************************************
> *******************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
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