Cylinder Group Size reduces in UFS.


 
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Operating Systems Solaris Cylinder Group Size reduces in UFS.
# 1  
Old 03-18-2004
Cylinder Group Size reduces in UFS.

Hi all,
I am working on Solaris 8 . Its default file system is UFS. My problem is regarding to the file system. I create two partition 1) / 1.2 Gb and 2) /home 4.5 GB
In root partition there were 76 Cylinder groups ,when I was traversing the Cylinder Groups I found that the length of one cylinder Group was 32320 sector long. Up to 32 cylinder groups that length was absolutely fine ,when I jump to the 33rd Cyl. Grp. That difference reduces to 31296 sectors it means it reduces by 1024 sectors. And it happens at every multiple of 32 cylinder groups. Is there any information regarding this in SuperBlock or in Cylinder Summary Block Structure.

In 2nd case of /home partition there were 286 cyl. Grp. , the length of 1 Cylinder Group was 98848 , In this case also when I jump to 32nd to 33rd Cylinder Group the length reduces to 2048 sectors,It means length becomes 96800 sectors. It happens every multiple of 32 means 64th to 65th , 96th to 97th like this.
This difference usually came when I create a big partitions but when I create 1 gb partition then this difference became 1024 sectors.
Please help me to solve this problem how can I got this value or is there any formula.

With Thanks and Regards

Sundeep Saini
# 2  
Old 03-18-2004
I'm not sure what this is, but if I had to guess I'd say those short groups are where the backup superblocks are. It reserves a certain amount of space for those maybe.
# 3  
Old 03-18-2004
First, please read our rules. I deleted the crosspost.

Second, there is is one backup superblock per cylinder group.

Third, I have just looked at three Solaris filesystems and I can't find any that have different sized cylinder groups. If they did, I don't see how the filesystem code would work. I must believe that you are in error in thinking otherwise.

And if they did, why would you care about the internal file system geometry?
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