D&C Lug - Home Page
Devon & Cornwall Linux Users' Group

[ Date Index ][ Thread Index ]
[ <= Previous by date / thread ] [ Next by date / thread => ]

Re: [LUG] Backup servers



On Wednesday 08 Oct 2003 12:56 am, Neil Williams wrote:
>
> > Thanks for the suggestions. With the 10 - 20 minute cron job - would that
> > copy open files? We have a large number of transactions every day (I work
>
> Depends on what process has opened the file and how it has locked the file.
> cron is just the daemon that executes the script/program etc. Whether the
> file can be copied is up to the permissions/setup of the script/program
> called by cron. If it's a bash script, it would probably come down to whose
> crontab you use to install the cron task.

I have no idea how to test this - the program is provided by our IT suppliers 
and it's workings are a mystery to me. And to them sometimes it seems.

> > mis-quote Murphy). It is almost certain that there would be open files at
> > the time of the cron job.
>
> But each individual file wouldn't be open all the time, so cron / your
> script might get a chance to copy when the file is closed whilst the main
> process moves on to another task. e.g. MySQL only locks the tables when an
> insert or update is in progress (and even that's configurable) - select
> queries can wait until other processes are done.
>
> What size files are you thinking would be open?
> What type?
> How many?

Absolutely no idea. This is just conjecture at the moment - i.e. is this 
somewhere in the realms of possibility.

> Isn't this getting into areas where RAID would become a practical solution?
> I have little experience of RAID but I believe it could give you a mirror
> type copy on the first server (which would deal with the immediacy of the
> data) and the backup server could copy that freely.

We already have RAID on our server, but it is RAID 5 which is not strictly a 
copy - more an amalgamation over the three disks (+1 hot spare). Given the 
option I would change/upgrade to RAID 10 for the read performance gain at 
least.

Thanks again,

Mark
-- 
For information on Newquay, Cornwall, and the surrounding area:
http://www.Newquay-Plus.co.uk

--
The Mailing List for the Devon & Cornwall LUG
Mail majordomo@xxxxxxxxxxxx with "unsubscribe list" in the
message body to unsubscribe.


Lynx friendly