Re: Autoextend for rollback

A copy of this was sent to John Higgins <JH33378_at_deere.com> (if that email address didn't require changing) On Fri, 18 Jun 1999 22:18:42 -0500, you wrote:

>Yes, it is beautiful to see two points of view -- logically presented without a lot of
>emotion!
>
>How would you guys modify your views if you were using raw devices? Is it even possible
>to allocate just part of a raw device and then use autoextend?
>

raw & autoextend are pretty much mutually exclusive options. You can use it, but it doesn't really make sense. You have to give us the device anyway, nothing else can use it (safely) so just allocate it all up front.

OTOH, with cooked file systems, when the database isn't useing the disk, other things can. On a smallish system -- this can be great.

>What if you were using RMAN for backups? RMAN does not backup unused space. What IS
>unused space for this purpose in the rollback and temp tablespaces?
>

the rollback segments (in my environment) are always "full". I always have them allocated out. they aren't really empty.

that and I don't use rman myself yet. still stuck on tar...

>What if the RMAN backups used Veritas NetBackup over TCP/IP (100MBS ethernet) to shared
>tape drives?
>

I guess we are talking economies of scale here. I run on a fairly smallish machine. I DBA the machine when i can. it sort of has to run itself lots. letting rollback and temp grow to some reasonable upper bound is something I need to do. I shrink it before backups to make them go faster.

If i did hot backups (i don't, i do full cold once a week and run archive log mode the rest of the time) -- then space isn't as much of a consideration since the backup time doesn't affect the uptime of the database.

there are lots of variables involved. If i was in a large'ish data center, with 24x7 DBA support -- i wouldn't use autoextend. I wouldn't need to.

OTOH, if I was running a database everyone used but was smallish and didn't have a dedicated full time support staff (my database for example) and I wanted the occasional large transaction to succeed without someone having to call me and increase the rollback segments -- i would use autoextend (as i do)...

[snip]

--
See http://govt.us.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Fine Grained Access Control", added June 8'th  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Sat Jun 19 1999 - 14:03:34 CDT