Dimon's blog
This blog is a sort of notebook for writing down things that are undocumented or hard to remember. Occasional musings or rants may also appear. Feel free to comment and use as you see fit, but at your own risk!
2011-02-01
2011-01-25
Oracle log switches per day
I just wrote this up to count the number of archived logs generated per day:
SELECTThere is probably an easier and faster way. Comments welcome.
trunc(first_time) t,
count(*)
FROM v$log_history
WHERE trunc(first_time) IN
(SELECT DISTINCT
trunc(first_time)
FROM v$log_history)
GROUP BY trunc(first_time)
ORDER BY t;
Labels: oracle
2011-01-18
DS4000 (and, possibly, others) usable drive capacity
A quote from IBM System Storage DS4000 and Storage Manager V10.30:
Note: The usable disk space is less than overall disk capacity. Consider these usable capacity amounts for storage capacity calculation issues:
73.4 GB formatted capacity is equal to 67.860 GB usable capacity.
146.8 GB formatted capacity is equal to 136.219 GB usable capacity.
300 GB formatted capacity is equal to 278.897 GB usable capacity.
500 GB formatted capacity is equal to 465.161 GB usable capacity
The usable capacities are what the SMclient will report as storage that can be used by the hosts. We arrive at this number by the following steps:
1. Take the listed raw disk amount (listed in decimal, as the storage industry standard dictates) and divide by 1.073742 to get a raw binary capacity (1 decimal GB =
1,000,000,000 bytes. One binary GB = 1,073,741,824 bytes (2^30 bytes)).
2. Subtract out the 512 MB DACstore region (region that holds configuration information) after converting the DACstore to binary.
3. This gives you the usable binary capacity that can be utilized by hosts and is what the SMclient will report to you as usable capacity.