Pau Lo
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redo logs and control files
can anyone elaborate (in laymans management freindly terms) the risks associated with storing all redo logs and control files on the same drive? I have seen a few articles stating they should be stored on seperate discs, can I ask why? do oracle themselves have a view on this, and any artciles to back their view up?
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Even on raided storage I tend to move things around onto different devices as much as possible. What happens if you have a failure in the raid controller ? Or the enclosure where the disks are spontaneously combusts ?
Admittedly, if you're on a SAN or a VM, there's a whole lot more there that is invisible to the DBA. If the SAN admin assigns you a couple of disks you have no idea if they are on separate physical devices or the same one.
For backups, you're only as good as the last time the backup was taken. If you have a backup, and a copy of your redo logs and the backup of your archive log destination you can restore to the point of failure (I had a sysadmin disconnect my datafile drive once in error. Between the backups and the online redo logs that were still on another volume I recovered right up to the point where the disconnect occurred and the users lost zero data).
It would be a very rare installation where the users would be happy with any data loss, even if it was "only a day".
They might be able to "live with it", but I doubt they'd be happy and you never want to be the DBA who has to tell his boss that you didn't have sufficient redundancy or backups built into your disaster recovery plan to mitigate as much loss as is humanly possible.
Of course there more disaster proof you need your system to be the more it costs. You certainly want to hope that your bank has multiple redundant control in place including all sorts of hot offsite copying of data by the second as it happens (but I'm getting off track now).
Admittedly, if you're on a SAN or a VM, there's a whole lot more there that is invisible to the DBA. If the SAN admin assigns you a couple of disks you have no idea if they are on separate physical devices or the same one.
For backups, you're only as good as the last time the backup was taken. If you have a backup, and a copy of your redo logs and the backup of your archive log destination you can restore to the point of failure (I had a sysadmin disconnect my datafile drive once in error. Between the backups and the online redo logs that were still on another volume I recovered right up to the point where the disconnect occurred and the users lost zero data).
It would be a very rare installation where the users would be happy with any data loss, even if it was "only a day".
They might be able to "live with it", but I doubt they'd be happy and you never want to be the DBA who has to tell his boss that you didn't have sufficient redundancy or backups built into your disaster recovery plan to mitigate as much loss as is humanly possible.
Of course there more disaster proof you need your system to be the more it costs. You certainly want to hope that your bank has multiple redundant control in place including all sorts of hot offsite copying of data by the second as it happens (but I'm getting off track now).
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is it common to seperate the oracle software and all the relevant database files onto different drives as well?
dunno about who's doing what in common, but in general i have 5 drives
C: Operating system, D: oracle software, G: control files, redo files, archive logs, H: control files, redo logs, data files, I: backups
whenever wants to backup the server, i indicate they can only backup C, D and I
I tell them i'll do the rest.
backup software with for oracle built specific agents doesn't always work too well
that's just one reason to make a distinction ... failures and redundancy is still the main one
C: Operating system, D: oracle software, G: control files, redo files, archive logs, H: control files, redo logs, data files, I: backups
whenever wants to backup the server, i indicate they can only backup C, D and I
I tell them i'll do the rest.
backup software with for oracle built specific agents doesn't always work too well
that's just one reason to make a distinction ... failures and redundancy is still the main one
ASKER
also if you have routine backups, does that again mitigate the impact? is this more towards minimizing how much data you lose in relation to hardware failure? which if you do daily backups would be a days worth at most, as if the server goes boom I assume everything goes down..