LinuxQuestions.org
Help answer threads with 0 replies.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices


Reply
  Search this Thread
Old 09-15-2009, 03:09 PM   #1
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Rep: Reputation: 46
/dev/shm and all my drives are off by .1GB


Couple more questions, I think these might be less critical so making another post.

I just loaded a RHEL server through the GUI. When i do a df -h most of my drives appear to be .1GB less than what I entered when i created each partition. See below.

Also, what is /dev/shm and why does it say tmpfs, everything else i've ever seen says none instead of tmpfs. I'm sure I didn't do something I should have.


Filesystem Size Used Avail Use% Mounted on
/dev/sda2 3.0G 232M 2.6G 9% /
/dev/sda10 66G 180M 62G 1% /data1
/dev/sda9 3.0G 69M 2.7G 3% /home
/dev/sda8 3.9G 73M 3.7G 2% /tmp
/dev/sda7 3.9G 107M 3.6G 3% /var
/dev/sda6 5.9G 1.3G 4.3G 23% /usr
/dev/sda5 47G 181M 44G 1% /opt
/dev/sda1 122M 11M 105M 10% /boot
tmpfs 1014M 0 1014M 0% /dev/shm
 
Old 09-15-2009, 07:20 PM   #2
chrism01
LQ Guru
 
Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.8, Centos 5.10
Posts: 17,240

Rep: Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324
1. There's a very small amt of overhead for partition table info at the start of each partition. There's a larger discrepancy caused by manufacturers using powers of 10 instead of powers of 2 (what a computer uses). For small amts, the diff is small, but increases proportionately as nums get larger.
http://en.wikipedia.org/wiki/Gibibyte & links therein.

2. iirc, /dev/shm is df's way of displaying swap partition. Try fdisk -l (lowercase L) as an alternate view.
See also du, which can give slightly different results again...
http://linux.die.net/man/1/du
http://linux.die.net/man/1/df
 
Old 09-15-2009, 07:38 PM   #3
lutusp
Member
 
Registered: Sep 2009
Distribution: Fedora
Posts: 835

Rep: Reputation: 102Reputation: 102
Quote:
Originally Posted by rjo98 View Post
Couple more questions, I think these might be less critical so making another post.

I just loaded a RHEL server through the GUI. When i do a df -h most of my drives appear to be .1GB less than what I entered when i created each partition. See below.

Also, what is /dev/shm and why does it say tmpfs, everything else i've ever seen says none instead of tmpfs. I'm sure I didn't do something I should have.


Filesystem Size Used Avail Use% Mounted on
/dev/sda2 3.0G 232M 2.6G 9% /
/dev/sda10 66G 180M 62G 1% /data1
/dev/sda9 3.0G 69M 2.7G 3% /home
/dev/sda8 3.9G 73M 3.7G 2% /tmp
/dev/sda7 3.9G 107M 3.6G 3% /var
/dev/sda6 5.9G 1.3G 4.3G 23% /usr
/dev/sda5 47G 181M 44G 1% /opt
/dev/sda1 122M 11M 105M 10% /boot
tmpfs 1014M 0 1014M 0% /dev/shm
Please read my reply to your prior thread on this issue. You are going to regret this configuration, in fact, there's a chance it won't boot.
 
Old 09-16-2009, 08:46 AM   #4
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Original Poster
Rep: Reputation: 46
Quote:
Originally Posted by chrism01 View Post
1. There's a very small amt of overhead for partition table info at the start of each partition. There's a larger discrepancy caused by manufacturers using powers of 10 instead of powers of 2 (what a computer uses). For small amts, the diff is small, but increases proportionately as nums get larger.
http://en.wikipedia.org/wiki/Gibibyte & links therein.
So is there a way to get them to be what i actually wanted? I don't care if I have to reload the server, I haven't done much on it yet.

Quote:
Originally Posted by chrism01 View Post
2. iirc, /dev/shm is df's way of displaying swap partition. Try fdisk -l (lowercase L) as an alternate view.
See also du, which can give slightly different results again...
http://linux.die.net/man/1/du
http://linux.die.net/man/1/df
So its not a problem it says tempfs as opposed to none?
 
Old 09-16-2009, 08:47 AM   #5
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Original Poster
Rep: Reputation: 46
Quote:
Originally Posted by lutusp View Post
Please read my reply to your prior thread on this issue. You are going to regret this configuration, in fact, there's a chance it won't boot.
Everything I've read on Linux in the past 3 months has said that you should manually create the extra partition. I still don't understand why you're saying it won't boot. In my server I have 2 drives RAID1 with a hot spare, and it sounded like in that other forum you linked to, you were saying it could be a problem if they are on other drives.
 
Old 09-16-2009, 10:41 AM   #6
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Original Poster
Rep: Reputation: 46
So what should I have put in to make my drives 4 and 6GB? I put in 4096 and 6144 (or at least I thought I did haha).
 
Old 09-16-2009, 12:01 PM   #7
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Original Poster
Rep: Reputation: 46
Not sure if this helps to show what I did wrong

Disk /dev/sda: 146.5 GB, 146557370368 bytes
255 heads, 63 sectors/track, 17817 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 16 128488+ 83 Linux
/dev/sda2 17 408 3148740 83 Linux
/dev/sda3 409 539 1052257+ 82 Linux swap / Solaris
/dev/sda4 540 17817 138785535 5 Extended
/dev/sda5 540 6805 50331613+ 83 Linux
/dev/sda6 6806 7588 6289416 83 Linux
/dev/sda7 7589 8110 4192933+ 83 Linux
/dev/sda8 8111 8632 4192933+ 83 Linux
/dev/sda9 8633 9024 3148708+ 83 Linux
/dev/sda10 9025 17817 70629741 83 Linux
 
Old 09-16-2009, 08:36 PM   #8
chrism01
LQ Guru
 
Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.8, Centos 5.10
Posts: 17,240

Rep: Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324Reputation: 2324
In fdisk you can specify how much you want in GB; easier than blocks/cylinders. Also (of course) all partitions/disks in a RAID set should be of the same size.
In extreme cases you may even need them to be same make+model.
 
Old 09-17-2009, 10:11 AM   #9
rjo98
Senior Member
 
Registered: Jun 2009
Location: US
Distribution: RHEL, CentOS
Posts: 1,668

Original Poster
Rep: Reputation: 46
Yeah, i guess maybe i lost the space due to ext3 and whatever else it does by default to new partitions. guess i'll live with it showing 5.9 instead of 6 :-(
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
/dev/shm GazL Slackware 2 05-28-2008 09:39 AM
/dev/shm? icecube Linux - Hardware 3 03-14-2006 08:34 AM
use of /dev/shm kskkumar Linux - General 1 01-31-2006 02:55 PM
What is /dev/pts, /dev/shm? mrpc_cambodia Red Hat 1 10-18-2004 04:27 AM
/dev/shm sakeeb Linux - Software 9 06-05-2002 07:03 AM


All times are GMT -5. The time now is 03:01 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration