Questions about adding new disk

Garrett Cooper youshi10 at u.washington.edu
Mon Oct 2 13:30:21 PDT 2006


On Oct 2, 2006, at 1:19 PM, Daniel Johansson wrote:

> Hello, I've just bought two new Seagate SATA drives and a Promise  
> TX4 SATA300 controller. The disks and the controller is working  
> fine but I'm a little confused how I should setup them.
>
> First of all I'm running FreeBSD 6.1. The disks are two 320 GB  
> drives who I'm going to use for storage. Backups, movies, music etc.
>
> I've read the handbook about adding new disks and I've got them  
> setup but here are my questions.
>
> 1. Should I use soft updates or not on the new disks? The handbook  
> doesn't mention anything about using -U to newfs to setup soft  
> updates. The installer is using it on the system disks but is it a  
> bad idea to use it on storage disks or why isn't it mention in the  
> handbook?
>
> 2. Is it a bad idea to use tunefs -m 0 ? I don't need any space  
> reserved for root at the disks but the man page mentions that I'll  
> loose performance when using -m 0. Will it be so much that the  
> extra space isn't worth the performance loss?
>
> 3. Should I use tunefs -o space or time? I guess space is the way  
> to go but again how much of a performance loss is there?
>
> If you replay to this email could you please CC it to me as I'm not  
> subscribed to this list.
>
> Thank you for you help.

My suggestions:

1. Turn softupdates on, or else if you lose power to the disk  
accidentally and some changes to the fs were in effect, you will  
possibly (20%~33% chance from my experience) lose data.

2. You want reserved space, or else fs'es fragment easily in the unix  
world, and you can still keep writing to an extent or another if  
you're root or privileged and you have reserved space IIRC.

3. It depends.. what do you want more and what is the role of the  
disk? If it's truly just storage and not used for a lot of swapping/ 
paging type applications, etc, think of using space over time.  
Otherwise, use time.

-Garrett


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