Cold journey downwards to Slough, and somehow I managed to completely tear to shreds the back of my shirt just by stretching too much, a bit like the Incredible Hulk. Oh dear, at least I did not turn green.
Astonishingly quiet attendance at the first RAC sig of the year. Not sure whether it is a sign of economic doom and gloom, or a reflection on the agenda, which seemed a bit light, and far too much vendor led.
Julian Dyke outgoing chairman gave a valedictory speech as he has to stand down as chairman of the RAC SIG, now that he has been elected to the UKOUG board.
The days agenda has a theme around replication – not a bad idea having a theme, as I say just a shame it was so vendor led.
Survey of who is using what still going:
#nodes in cluster: vast majority of 2 a sprinkling of 3 and 4.
vast majority running on Linux almost 50/50 32bit and 64bit, majority on RHEL. none on oracle enterprise linux.
sprinkling on windows, a little bit more on Solaris Sparc, and a couple on HP-UX.
A few on 9.2, a couple on 10.1, vast majoirty on 10gR2, no one has got 11.1 RAC in production.
No one using RAC with iSCSI, a couple on NAS, and most on FC.
EMC largest storage vendor, a few HP’s, IBMs, Netapp.
A good number using ASM, a few with OCFS1/2
I think these survey numbers have been fairly constant for a while now.
Oracle Support Update – Phil Davies.
Usual support update from Phil.
Of note is that 10.2.0.5 will be the terminal release, for 10gR2.
Looks like an interesting bug in 188.8.131.52 Rolling upgrade to ASM fails MetaLink Note: 742647.1 There is a patch for this issue.
Streams Based Replication – Martin Bach
Martin is one of the most knowledgeable guys around, and in December he obtained the Oracle Certified Master qualification.
This was a nice presentation giving a grounding in how Oracle Streams works.
Streams is versitile but complex, the Oracle documentation runs to 3 manuals just for streams. As streams is not really a well used database feature there can be a lot of bugs with it. Note 413353.1
There was also a good discussion of some issues Martin has encountered while running streams.
Minimising downtime when upgrading/migrating Oracle with Goldengate – Ian Richardson
Goldengate does replication including bi-directional replication
The architecture of goldengate seems quite similar to oracle streams, has a capture, paropagate, and deliver (or apply) process. It’s completely platform independent can use it to go from 1 type of platform to another, or indeed 1 oracle version to another. It does seem like a great way of minimising downtime during migrations/upgrades.
Lessons From a 2 year stretch with an extended RAC Cluster – Pavel Rabel
Extended RAC is having RAC nodes separated by quite a distance. This is lessons from BT.
In 11g docs Extended RAC is becoming an accepted architecture. ASM with normal redundancy can be used to spread the data across multiple disk arrays in the separate datacenters.
30KM between the two datacenters, I think he said 0.2ms ping round trip time.
Used ASM to migrate from original storage to new storage
Could not add/remove css votedisk while nodes were up, cluster downtime was required. Fixed 11g
ouch! They run dd on the incorrect disk
Created 3rd failgroup which meant some extents got mirrored within a datacenter
ASMLib using emcpower device, but after restart single path devices used after restart.
Found accessing local devices were 10-20% times faster than accessing the remote disks.
11g ASM benefits for extended RAC
ASM_PREFFERED_READ_FAILURE_GROUPS allows you to specify only local access to diskgroups – allowing secondary extents to be read as well, rather than just always primary extents
FAST Mirror Resync changes are tracked
Contiuent Replication & Oracle – Eter Pani
I did not like this talk. I’m afraid it semed a little shambolic.
Oh my god, he has just said it’s “almost working” does replication master-slave, and master-master might work someday. originally built with mysql. Might work with oracle.
Continuent is cheap, that seems to be the main selling point.
Continuent seems to work by extracting sql from the redo logs and firing these sql statements at the target database. No parallel applier.
I don’t think you would want to use this product for serious Oracle deployments.
Next meeting RAC & HA SIG meeting is 16th June in London, see you there!