I can delete the file, but it takes hours to recreate, so I figured that I'd
run any tests you guys want to see first.
-Robert
On Jan 3, 2010, at 5:19 AM, Joel Becker wrote:
> On Sat, Jan 02, 2010 at 04:47:58AM +0900, Robert Smith wrote:
>> Just thought I would let you guys know that creating a 20TB file was
>> successful. I even appended data to the end of it. Any operations on the
>> file are completely useless because they take way to long. A appended
>> "hello" to the end of the file no problem, but tail -n 1 {filename} yielded
>> nothing except a lot of disk read after 159minutes of waiting.
>
> Wow, that's a lot of waiting. I suspect it's the fault of
> tail(1). You asked for the last line of the file (tail -1). I bet
> tail(1) is reading the entire file line-by-line in order to calculate
> the last line. This has to be much slower than reading it at optimal
> hunks (with your 500MB/s disks). Conversely, appending is easy because
> the kernel just starts at the end of the file. No need to read the
> existing 20TB.
> What other operations are 'completely useless'? The expectation
> would be that random I/O is as fast as ever. How long does deleting
> take?
>
> Joel
>
> --
>
> "The trouble with being punctual is that nobody's there to
> appreciate it."
> - Franklin P. Jones
>
> Joel Becker
> Principal Software Developer
> Oracle
> E-mail: joel.bec...@oracle.com
> Phone: (650) 506-8127
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