Why mkfile decreases available memory?

Hi,

we are experiencing very odd behavior. After "mkfile 1g <somefile>" the available memory seen through vmstat memory free column decreases by the same ammount. It doesn't matter where the <somefile> is located, even when the file is on NAS, the available memory decreases. When the file is removed, the memory returns to its original. The mpstat shows another odd behaviour, one of the processors goes on 100% sys time usage. We can replicate this on several Solaris 10 SPARC machines but we cannot replicate it on Solaris 10 x86 machines. What's going on? The mkfile is used only to replicate the problem, we have found this problem during our regular backup procedure that almost nocks down Oracle server.

SunOS 5.10 SUNW,SPARC-Enterprise
32G RAM
Sparc Enterprice M4000 Server

Thanks, Jan

Do you have enough swap space ?
I looked for a moment in man page and says

oracle@ldr-orc ~ $ vmstat 2
kthr memory page disk faults cpu
r b w swap free re mf pi po fr de sr m1 2m m1 m1 in sy cs us sy id
0 0 0 43853416 28854664 76 351 281 3 3 0 514 22 446 14 14 1115 10023 1417 0 2 98
0 0 0 42814872 27580328 0 33 128 0 0 0 0 0 668 0 0 1250 11827 541 0 2 98

---------- Post updated at 05:24 PM ---------- Previous update was at 05:23 PM ----------

The issue with 100% sys utilization was identified as bug 6886536