There are already a lot of blogposts and presentations done about Hybrid Columnar Compression and i am adding one more blogpost to that list. Recently i was doing some small tests one HCC and noticed that that inserts on a HCC row didn’t got compressed and yes i was using direct path loads:
DBA@TEST1> create table hcc_me (text1 varchar2(4000)) compress for archive high;
KJJ@TEST1> insert /*+ append */ into hcc_me select dbms_random.string('x',100) (more...)
I noticed something for the first time tonight when I was playing around in the Enkitec lab – something that I have been doing wrong for a while. When working in the lab, I often rely on the crsctl command to shut down the entire cluster stack for me. It’s really easy to use “crsctl stop cluster -all” followed by “dcli -l root -g ~/dbs_group /u01/app/220.127.116.11/grid/bin/crsctl stop crs” to get everything down (more...)
Yes that is true, i said it, cellcli can lie to you there are some special cases were the output of cellcli is not the reality and you should double check it’s output with your standard OS tools. So this the output if dcli calling cellcli on an Exadata rack from an client:
[root@dm01db01 ~]# dcli -g cell_group -l root cellcli -e list cell attributes cellsrvStatus,msStatus,rsStatus
dm01cel01: running running running
dm01cel02: running running running
We had a client that was running into a strange issue on their Exadata where new connections coming in through the SCAN were failing. After doing some troubleshooting, it was discovered that it was related to one of the SCAN listeners not properly accepting requests from new sessions. The VIP and listener were running, and everything looked normal.
We had the following SCAN setup:
On Exadata the local drives on the compute nodes are not big enough to allow larger exports and often dbfs is configured. In my case I had a 1.2 TB dbfs file system mounted under /dbfs_direct/.
While I was doing some exports yesterday I found that my dbfs wasn’t mounted, running quick crsctl command to bring it online failed:
[oracle@exadb01 ~]$ crsctl start resource dbfs_mount -n exadb01
CRS-2672: Attempting to start 'dbfs_mount' on 'exadb01'
I’ve previously written about a problem I encountered when kdump is configured to write to an NFS location with UEK (in Exadata software version 18.104.22.168.1). I’m please to report that the root cause of the problem has been identified and there is a very simple workaround.
There were some frustrating times working this particular SR, the most notable being a response that was effectively, “It works for me (and so I’ll (more...)
I seem to be getting a lot of surprising performance results lately on our X-2 quarter rack Exadata system, which is good – the result you don’t expect is the one that teaches you something new.
This time, I was looking at using a temporary tablespace based on flash disks (more...)
Oracle has released the much-anticipated version of cellsrv compatible with Oracle Database 22.214.171.124 (patch #16980054). Before thinking about upgrading, read MOS note #1571789.1 carefully. Unless you are planning to run database 12c on your Exadata, it would be advisable to continue down the 11.2 branch (more...)
Today, Oracle announced the Exadata X4-2 model. The X4 has some considerable improvements, namely:
- 12-core Intel Xeon e5-2697 CPUs, up from the 8-core models found in the X3-2 (hello, database licenses!)
- 256GB RAM per database server, upgradeable to 512GB
- 96GB RAM per storage server
- 800GB Sun Flash F80 cards (more...)
Exadata Maximum Availability Architecture from Yunus Emre Baransel
There were problems that affected UEK and NFS when 126.96.36.199.1 was initially released (as covered by Andy Colvin). As mentioned in the comments of Andy’s post: Oracle released an updated ISO with fixes for this problem (patch 16432033).
There were also problems with kdump not (more...)
Recently we noticed that imageinfo was displaying the following information at a customers site. Imageinfo was not displaying data i suspected, so a quick little blogpost about what was going on there.
[root@dm01db01 ~]# dcli -g /opt/oracle.SupportTools/onecommand/dbs_group -l root "imageinfo | grep 'Image version'"
dm01db01: Image version: 11.2. (more...)
Of all the claims I make about SSD for Oracle databases, the one that generates the most debate is that placing redo logs on SSD is not likely to be effective. I’ve published data to that effect in particular see Using SSD for redo on Exadata - pt 2 (more...)
Prior to storage server software version 188.8.131.52.0 (associated with Exadata X3), Exadata Smart Flash Cache was a “write-through” cache, meaning that write operations are applied both to the cache and to the underlying disk devices, but are not signalled as complete until the IO to the (more...)
Relational DBMS used to be fairly straightforward product suites, which boiled down to:
- A big SQL interpreter.
- A bunch of administrative and operational tools.
- Some very optional add-ons, often including an application development tool.
Now, however, most RDBMS are sold as part of something bigger.
With cellcli you can run the calibrate command, this will measure the performance of your harddisks and flashcards. It will eventually report to you the throughput and amount of IOPS that was measured during the calibrate, it will also report to you which luns are not performing up to par.
As part of my Cloud Control journey I encountered a strange problem where I got the following error for few Exadata Storage Server (cell) targets:
Metric evaluation error start - oracle.sysman.emSDK.agent.fetchlet.exception.FetchletException: em_error=Failed to execute_exadata_response.pl ssh -q -o ConnectTimeout=60 -o BatchMode=yes -o StrictHostKeyChecking=no -o (more...)
Thanks to all those who came to my session "Are Indexes Unnecessary in Exadata" at Oracle Open World 2013. Considering it was late afternoon of the last day of the conference, especially after the appreciation concert, it was a pleasure to see a packed room. Judging by the interaction I (more...)
I heard a strange report from a client late last week - they weren't getting any smart scans on their Exadata - a data warehouse, no less (and we checked to see if cell_offload_processing was set to true). Queries would run normally, but for some reason, the "cell physical IO (more...)