Re: Fun in the Sun with Solaris 9

From: Nigel P. Longbottom (not_at_all.valid)
Date: 07/22/04 

Date: Thu, 22 Jul 2004 22:22:05 +0100

On 22/7/04 7:03 am, in article m3k6wwd1dq.fsf@magma.savecore.net, "Frank
Cusack" <fcusack@fcusack.com> wrote:

> On Wed, 21 Jul 2004 21:31:46 +0100 "Nigel P. Longbottom" <not@all.valid>
> wrote:
>> In the meantime - I had been doing some experimentation myself and
>> discovered that if I turned on logging and changed the mirroring read
>> strategy from round-robin to geometric, I got backup read speeds of between
>> 10Mb/s to 30Mb/s (compressed)!
>
> What is the geometric strategy? (use knowledge of proximity of last read
> to last known head position?)
>
> /fc

Thanks for the response. After Richard's comments, I'm glad some people
jumped in to clarify. Don't worry - I'm not that bad to start backing up to
CD-RW and yes - my tone can be a bit subtle!

I suppose my real point was a dig at Sun support. My initial query was about
backup rates to tape but I ended up being told that the problem was due to
mounted filesystems. With the competition in UNIX markets, I would say Sun
is damaging itself by saying not to backup while filesystems are mounted
(and they were adamant about this). I've been doing this for years
(obviously while the filesystems are quiet i.e. Oracle is shut down and the
servers are not active 24x7) and have no problems when restoring from these
backups in a Disaster Recovery exercise.

The other systems I work on - namely IBM AIX are quite happy to suggest you
backup when the filesystems are 'quiescent' (as they happily term it).

As for geometric read strategy - it's one of the options that you can assign
to mirrors using the metaparam command. Its recommended if you have large
sequential reads.

Relevant Pages

  • Re: Mirrored Folders
    ... > Yes its called backup, there are many different backup apps ... mirroring, which is very different from backup. ... Secure backup needs to be on media stored externally to the ... >> I want to create a mirrored folder so that the same files can ...
    (microsoft.public.windowsxp.general)
  • Re: ext4 features
    ... I compare all ctimes with the time of the last ... backup and do incremental on the newer ones. ... If the changes to these files are very infrequent compared to nanoseconds, ... all other filesystems will profit even ...
    (Linux-Kernel)
  • Re: Recovery from 3rd Party Backup Software
    ... yogi wrote: ... Mirroring is not a viable backup method. ... to use software mirroring. ...
    (microsoft.public.windowsxp.perform_maintain)
  • Re: Best backup
    ... Mirroring, in this case RAID 1, is for backup in case of hard drive failure. ...
    (microsoft.public.windowsxp.general)
  • Re: Disaster recovery planning
    ... > Here's how I plan to recover a system from a level 0 backup to ... boot in single user mode, fix fstab and devices, restore other filesystems ... install floppies -- I think you get dumpand restore, ...
    (freebsd-questions)