Defragmentation - SUMMARY

From: Adnan Niazy (
Date: Wed Nov 11 1998 - 02:39:48 CST

To everyone on the Sun-Managers list: I present the following summary.

I did receive a significant number of responses. In general, they break
down into three schools of thought:
1. > With Solaris and Unix in general there is no requirement for
defragmentation, the file system does a decent job on its own.

> The Unix file system is pretty resistant to fragmentation.
     The standard Unix solution to
> fragmentation is to back up and then restore the filesystem. Unless you are
> seeing real performance degradation due to fragmentation, you are probably
> safe to ignore fragmentation entirely.

> UFS is an auto-defraging filesystem. It works to keep itself defragged all the
> time. A defrag tool is unecessary.

> The standard filesystem (aka 4.3) does not require defragging.
> Just keep the disks less than 90% full to optimize performance.

There were around a dozen responses supporting this opinion.

2. - The Second school of thought was to run the Veritas File System.

> I suggest running Veritas file system for so much diskspace. Veritas file
> system (vxfs) allows you to run fsck on 4Gb Harddisk in few seconds.

> I believe that Veritas File System software (SUN product codes VFS-3.2-B
> & VFS-3.2-DS-L) provide this functionality
> UFS tries to defragment as it allocates. VxFS is probably worth considering
> as it does extent allocation and logging which would probably make a good
> bit of difference here.
> UFS file systems are always slightly fragmented. UFS was not designed to
> handle very large files. I recommend
> using Veritas VxFS for efficient access to gigabyte-sized files. Sun sells
> this as an option.

> It depends on which filesystem you're using. If it's ufs (the normal one)
> then there's no utility to defragment, but the filesystem is good enough
> that it's usually not necessary anyway. If you're running vxfs (Veritas)
> then there is a utility fsadm which performs defragmentation.
> /etc/vfstab will tell you which type each filesystem is.

As well as several other similar replies..

3 - The third group suggested a product by Eaglesoft:

> I have been using a product called DiskPak Online from Eaglesoft
> ( which does this job. They have an even more
> sophisticated package for disk access acceleration, called SEEKRite.

> Another option, if you create files and leave them in place for a long
> time, is a third-party disk defragmenter/sorter
> called Eagle DiskPak. I think you can download a demo that will let you see
> how fragmented UFS is from

> There is a product From Eagle that does it,
> but it does not work with RAID systems.

As well as a few others along this line, no affiliation to the company

There was a referral to the following website:
(and search for: "Chests of drawers and brainwashing") - It talks about
the defrag problem.

A fourth, unrelated suggestion was that I was remiss in addressing the
letter to "Gentlemen", as there are ladies present, too....
For this I apologize, but I had handed the letter and email address to
the secretary (aka "the wife"), and neglected to tell her that it was
directed to an internet forum.
She thought it was an inquiry to an individual in an office and used the
standard business letter formula (which, yes, I know is also
inappropriate these days).
Therefore, my apologies to the list for the salutation and my
acknowledgement of the presence and contribution of women in the field.

Thank you to everyone for taking the time to respond and for helping us
resolve this issue.

Adnan Niazy
King Abdulaziz City for Science and Technology
Institute of Astronomical and Geophysical Research
Riyadh, Saudi Arabia

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