read data from file from a specific duration

Hi,

i have log file which keeps on updating almost ever minute but i have certain string in log which will only be displayed between specific time. so i need to search for that string and copy the details starting from that string and stop at certain string below that.
example: log file contains as below
1243
123214
wtewds
243243
starting update
1234 records updated
985 records updated
10 records updated
final update
400 records updated
update completed
df[lsfadmgld
df
asdfg
ds'g
sd'g
ds
g'sd'g
sdg
starting update
134 records updated
85 records updated
104 records updated
final update
450 records updated
update completed
mb dmnb
mflmfnbvc
svmdknb
sd,vfl;sb

i need to copy the contents of this log file starting from "starting update" till "update completed" into another file. these lines will be displayed almost 20 to 30 times in a day but i need to search for a specific duration say 6pm to 11pm and i need to copy for this duration irrespective of number of times the string are displayed.

I don's see the time in your sample.

awk '/starting update/,/update completed/' yoursample.log  > another.file

Thanks for the help. for the log file below can i use the same awk command. and i want the output file to include the record updated both times.

1243
123214
wtewds
243243
bla bla bla===starting update===
1234 records updated
985 records updated
10 records updated
final update
400 records updated
bla bla bla :::::::update completed::::::::
df[lsfadmgld
df
asdfg
ds'g
sd'g
ds
g'sd'g
sdg
bla bla bla===starting update===
134 records updated
85 records updated
104 records updated
final update
450 records updated
bla bla bla :::::::update completed::::::::
mb dmnb
mflmfnbvc
svmdknb
sd,vfl;sb