zfs discuss - Dec 2008 - ZFS boot and data on same disk - is this supported?

I have read the ZFS best practice guide located at
http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide

However I have questions whether we support using slices for data on the 
same disk as we use for ZFS boot. What issues does this create if we 
have a disk failure in a mirrored environment? Does anyone have examples 
of customers doing this in production environments.

I have a customer looking to use ZFS boot but they only have two disks 
in their server and it is not connected to a SAN. They also need space 
for data what is he best recommendation?

Please respond to me directly as I am not on this alias.

Shawn

On Fri 19/12/08 14:52 , Shawn Joy Shawn.Joy at Sun.COM
sent:
> 
> I have read the ZFS best practice guide located at
> http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide
> However I have questions whether we support using slices for data on the
> same disk as we use for ZFS boot. 
Why would you want to do this instead of giving ZFS the whole disk?  Do you have
compelling reasons to use UFS rather than ZFS filesystems for data?
> What issues does this create if we 
> have a disk failure in a mirrored environment? Does anyone have examples
> of customers doing this in production environments.
> 
Use the whole disk for ZFS.
> I have a customer looking to use ZFS boot but they only have two disks 
> in their server and it is not connected to a SAN. They also need space 
> for data what is he best recommendation?
> 
Use the whole disk for ZFS.
> Please respond to me directly as I am not on this alias.
> 
Post here, read here :)

-- 
Ian

On Friday 19 December 2008 03:32:01 Ian Collins wrote:
> On Fri 19/12/08 14:52 , Shawn Joy Shawn.Joy at Sun.COM sent:
> > I have read the ZFS best practice guide located at
> > http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices
> >_Guide However I have questions whether we support using slices
> > for data on the same disk as we use for ZFS boot.
>
> Why would you want to do this instead of giving ZFS the whole disk?
>  Do you have compelling reasons to use UFS rather than ZFS
> filesystems for data?
I find ZFS''s eager to monopolize the disk quite irritating: sometimes
there OSs on the same disk.
BTW, how much does ZFS slow down (on average) when using 
slices instead of the whole disk?

On 19 December, 2008 - Nico Sabbi sent me these 0,8K bytes:
> On Friday 19 December 2008 03:32:01 Ian Collins wrote:
> > On Fri 19/12/08 14:52 , Shawn Joy Shawn.Joy at Sun.COM sent:
> > > I have read the ZFS best practice guide located at
> > > http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices
> > >_Guide However I have questions whether we support using slices
> > > for data on the same disk as we use for ZFS boot.
> >
> > Why would you want to do this instead of giving ZFS the whole disk?
> >  Do you have compelling reasons to use UFS rather than ZFS
> > filesystems for data?
> 
> I find ZFS''s eager to monopolize the disk quite irritating:
sometimes
> there OSs on the same disk.
> BTW, how much does ZFS slow down (on average) when using 
> slices instead of the whole disk? 
Nothing, but it speeds up if you give it the whole disk by enabling
write cache in the drives, as it knows when it''s safe to have it on and
not.

/Tomas
-- 
Tomas ?gren, stric at acc.umu.se, http://www.acc.umu.se/~stric/
|- Student at Computing Science, University of Ume?
`- Sysadmin at {cs,acc}.umu.se

Nico Sabbi wrote:
> On Friday 19 December 2008 03:32:01 Ian Collins wrote:
>   
>> On Fri 19/12/08 14:52 , Shawn Joy Shawn.Joy at Sun.COM sent:
>>     
>>> I have read the ZFS best practice guide located at
>>> http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices
>>> _Guide However I have questions whether we support using slices
>>> for data on the same disk as we use for ZFS boot.
>>>       
>> Why would you want to do this instead of giving ZFS the whole disk?
>>  Do you have compelling reasons to use UFS rather than ZFS
>> filesystems for data?
>>     
>
> I find ZFS''s eager to monopolize the disk quite irritating:
sometimes
> there OSs on the same disk.
>   
The context here was using Solaris UFS slices with ZFS boot.  The answer
was don''t bother, use ZFS filesystems instead.

-- 
Ian.