It’s still a hot topic in my customer conversations: Should we use Oracle Data Guard or something else for providing disaster recovery?
I’ve written an explanation a while ago. Recently I also created a powerpoint slide comparing various features – in an attempt to be as unbiased as possible (I think I partly succeeded 😉
I’ve put the comparison in a static page on my blog and will update it any time I get new insights or think I can improve it otherwise.
Many customers these days are implementing Oracle on XtremIO so they benefit from excellent, predictable performance and other benefits such as inline compression and deduplication, snapshots, ease of use etc.
Those benefits come at a price and if you just consider XtremIO on a usable gigabyte basis, it does not come cheap. Things change if you calculate the savings due to those special features. Still, customers are trying to get the best bang for the buck, and so I got a question from one customer if it would make sense to place only Oracle datafiles on XtremIO and leave everything else on classic EMC storage. This would mean redo logs, archive logs, control files, temp tables, binaries and everything else, *except* the datafiles, would be stored on an EMC VNX or VMAX. The purpose of course is to only have things that require fast random reads (the tables) on XtremIO.
I can clearly see the way of thinking but my response was to change the layout slightly. I highly recommend to place everything that is needed to make up a database in a consistent way, on the same storage box.
In my last post on ZFS I shared results of a lab test where ZFS was configured on Solaris x86 and using XtremIO storage. A strange combination maybe but this is what a specific customer asked for.
Another customer requested a similar test with ZFS versus ASM but on Solaris/SPARC and on EMC VNX. Also very interesting as on VNX we’re using spinning disk (not all-flash) so the effects of fragmentation over time should be much more visible.
So with support of the local administrators, I performed a similar test as the one before: start on ASM and get baseline random and sequential performance numbers, then move the tablespace (copy) to ZFS so you start off with as little fragmentation as possible. Then run random read/write followed by sequential read, multiple times and see how the I/O behaves. (more…)
In my previous post on ZFS I showed how ZFS causes fragmentation for Oracle database files. At the end I promised (sort of) to also come back on topic around how this affects database performance. In the meantime I have been busy with many other things, but ZFS issues still sneak up on me frequently. Eventually, I was forced to take another look at this because of two separate customers asking for ZFS comparisons agaisnt ASM at the same time.
The account team for one of the two customers asked if I could perform some testing on their lab environment to show the performance difference between Oracle on ASM and on ZFS. As things happen in this business, things were already rolling before I could influence the prerequisites and the suggested test method. Promises were already made to the customer and I was asked to produce results yesterday.
Without knowledge on the lab environment, customer requirements or even details on the test environment they had set up. Typical day at the office.
In addition to that, ZFS requires a supported host OS – so Linux is out of the question (the status on kernel ZFS for Linux is still a bit unclear and certainly it would not be supported with Oracle). I had been using FreeBSD in my post on fragmentation – because that was my platform of choice at that point (my Solaris skills are, at best, rusty). Of course Oracle on FreeBSD is a no-go so back then, I used NFS to run the database on Linux and ZFS on BSD. Which implicitly solves some of the potential issues whilst creating some new ones, but alas.
Solaris x86
This time the idea was to run Oracle on Solaris (x86) that had both ZFS and ASM configured. How to perform a reasonable comparison that also shows the different behavior was unclear and when asking that question to the account team, the conference call line stayed surprisingly silent. All that they indicated up front is that the test tool on Oracle should be SLOB.
Background