The purpose of this blog is to highlight what you need to know about the IBM i POWER (AS400/iSeries) RAID controller cache and battery. I wrote this because I had 3 customers encounter cache battery problems in the last 7 days (yikes). I want IBM i users to understand what the cache battery is and how to respond when you get that first error message that lets you know to replace…not the one that tells you that your cache battery has died.
Disclaimer: AS400, iSeries, and POWER are IBM servers. IBM i is an operating system. I use them interchangeably to make it easier for folks to find what they want when searching the web.
IBM i POWER (AS400/iSeries) servers have disk controllers with cache memory to temporarily hold data between the processor and storage. The cache memory allows the server to run faster so the processor does not have to wait for the storage to “acknowledge” the data has been received and successfully saved.
The cache memory requires a battery to keep the data safe until it gets written to the storage media. So, if your server ever loses power the data in the cache memory is protected until power is restored.
How long does a cache battery last?
The cache battery will last about 2.5 – 3 years before it dies.
So, what happens when your cache battery “dies”? (OMG, is my system going to fail?)
When your cache battery dies, your system will run slower…much slower. That is because the RAID controller needs the storage subsystem to “acknowledge” the data has been successful saved. This process takes much longer than the RAID controller cache does.
Your system is safe. It will just take longer to process your workload.
The IBM i POWER (AS400/iSeries) server will give you a console error message – (SRC) “xxxx8009” – about 80 days prior to your battery end of life.
If you have IBM hardware support properly connected, IBM will notify you that they need to schedule a cache battery replacement at your convenience in 1-3 weeks.
If you do NOT have IBM hardware support, be on the lookout for this console error message. You have 80 days to fix it. Just don’t ignore the message.
The next message you may get – (SRC) “xxxx8008” – meaning the “Estimated time to error (days)” has reached 0, is telling you your cache battery is close to end of life…or completely dead. If so, your system will run slow until your cache battery gets replaced.
You should be aware that the cache battery is unique to the server model. So, an expert needs to diagnose the specific cache battery to order.
It takes about 30 minutes or so to power down your server, replace the cache battery and power your server back up.
Once installed, your IBM i POWER (AS400/iSeries) server RAID cache battery will be fine for another 2.5 to 3 years when it will need to be replaced again.
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https://www.source-data.com/ibm-i-on-power-server/
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https://www.source-data.com/cloud-400/
3) IBM I (iSeries/AS400) Disaster Recovery Options
https://www.source-data.com/cloud400-disaster-recovery/
4) IBM I (iSeries/AS400) Version Upgrade
