تنظیمات Cache Watermark Level در استوریج EMC
We set the cache low/high watermark levels to 30%/50%. I read some blogs, bloggers said EMC recommendation is 60%/80%. I would like to change the watermark levels as per EMC recommendation. what will happen when i change the watermark levels on production hours.
Storage Model: EMC Celerra NX-4
Backend: Clariion AX-4 5F8
Flare: 2.23.50.5.711
I’ll assume you are running Navisphere Manager 26 (with FLARE 23) and a newer version of Java. While running a recent version of Java is not an issue necessarily in itself; however, you most likely answered “Yes” to a Java prompt asking:
“Block potentially unsafe components from being run? (recommended)”
This appears when you access certain displays within Navisphere Manager such as “System Properties”. Instinctively, people select “Yes”, and I would agree it is recommended on webpages you aren’t familiar with; however, that will unfortunately break functionality within the GUI as you had experienced. I will mention though if you managed your array with Unisphere (via domain management), you wouldn’t get this prompt.
You can confirm you had (accidentally) answered: “Yes” if you only see the tabs:
1) General
2) Cache (NOTE: even though the Cache tab is displayed, several background Java scripts don’t run)
On the other hand if you properly selected “No”, then you’d see many more tabs:
1) General
2) Cache
3) Memory
4) Storage Access
5) Software
You have 2 solutions (*neither* requires disabling write cache or watermarks):
Solution #1
1) Close the GUI and clear both browser and java cache
2) When prompted, select “No” to the Java prompt
3) On the Cache tab modify in the following order:
a) Change the High Watermark first
NOTE: This is important as the GUI checks that Low watermark is < High watermark. If you were to try to change the Low watermark first, it would appear to not accept your input. However, in this case the new lw (60%) > old hw (50%).
b) Change the Low Watermark, then click OK
Solution #2
Modify via CLI:
1) naviseccli -h <SP A or SP B IP> setcache -l 60 -h 80
NOTE: only need to run on one SP as it is a “mirrored” option
2) naviseccli -h <SP A IP> getcache
3) naviseccli -h <SP B IP> getcache
NOTE: (optional) verify that both SP’s report the updated values