?
Solved

What is a holey file?

Posted on 1997-10-12
6
Medium Priority
?
861 Views
Last Modified: 2011-09-20
What is it? Why do they exist? Why I can't handle them as other files?
0
Comment
Question by:jlms
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
6 Comments
 
LVL 3

Expert Comment

by:EricKaplan
ID: 2007394
"holey" file ? are you sure you got that right ?

-Eric.
0
 
LVL 4

Author Comment

by:jlms
ID: 2007395
I think so...
0
 
LVL 3

Expert Comment

by:EricKaplan
ID: 2007396
Where did you get that info ? what OS ? ....
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 4

Accepted Solution

by:
rembo earned 200 total points
ID: 2007397


When you talk about holey files, I'm assuming
that you're talking about files which were
creating with empty checks via lseek.  

These are stored in the filesystem using
only header info, not real disk blocks.  However,
if you try to put this on to a tape, especially
with dd or something like that, it will try to
write the actual blocks.  

For example, you could lseek forward 2GB in a file
and then write 1 character.  Your file size is then
huge, but it actually only takes up one disk block
(this is in UFS, not any old SVR4 system).  However,
older filesystems can figure this out.

Anyway, the deal is you need to be careful with things
that might try to map these headers to real data.

So, the deal is, try not to create holey files :)
but if you do, just know what you're doing with
them and how you move them.  Try to use tar and
modern, ufs or vxfs filesystems.  

If there's a specific application you're wondering
about, let me know.  I'd be happy to help.

-Tony


0
 
LVL 4

Author Comment

by:jlms
ID: 2007398
I think I understand, and no, I don't have any application in particular in mind.

One last thing, how can I recognize one of this files?
0
 
LVL 4

Author Comment

by:jlms
ID: 2007399
I think I understand, and no, I don't have any application in particular in mind.

One last thing, how can I recognize one of this files?
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I have been running these systems for a few years now and I am just very happy with them.   I just wanted to share the manual that I have created for upgrades and other things.  Oooh yes! FreeBSD makes me happy (as a server), no maintenance and I al…
Java performance on Solaris - Managing CPUs There are various resource controls in operating system which directly/indirectly influence the performance of application. one of the most important resource controls is "CPU".   In a multithreaded…
Learn how to navigate the file tree with the shell. Use pwd to print the current working directory: Use ls to list a directory's contents: Use cd to change to a new directory: Use wildcards instead of typing out long directory names: Use ../ to move…
This video shows how to set up a shell script to accept a positional parameter when called, pass that to a SQL script, accept the output from the statement back and then manipulate it in the Shell.
Suggested Courses
Course of the Month15 days, 16 hours left to enroll

743 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question