Re: Question: Oracle Backup to NAS Device SATA vs.. SCSI vs. $$$

On Wed, 16 Mar 2005 09:29:47 -0600, Henslee, Jeff <jhenslee_at_wausauwindow.com> wrote:
> First and foremost - Thanks for your response.
My pleasure. This type of brainstorming is fun. Pardon me if anything I say is obvious, and _definitely_ take everything with a grain of salt since it is just brainstorming.

> Yes - but this is secondary. Recovery is primary concern. Since our disk technology is
> past end-of-life and management is unwilling to upgrade at this time, I need relief in doing any
> sort of data recovery (or disaster recovery).
>

...
> The issues range from backups beginning to run over onto multiple tapes and
> not having any money for an auto changer, to improving our restore and recovery time
> from the 32-36 hours it is now - to something a little more manageable (for me - since I am the poor fool
> that has to baby-sit a restore and recovery for that amount of time).
> (Begin-o-whine)
> We do have an SLA, but no one wants to address the real issues until there is a problem and then, obviously,
> it's too late, the disk array is down, and it's in the middle of month end close.
> (end-o-whine)

Gotcha, and I understand that type of environment. I used to work on a project that wasn't "business critical" but was "business important". That is, it was 24x7 but it didn't need to have 99.999 uptime, and, oh, it was down a ways on the budget list. Leads to some, ah, creative solutions to best utilize the resources available.

> What's your current performance and what do you want it to get to?
> For example, if you are currently shoving 50MB/s to the tapes, you are
> not going to get much performance increase if you are going to
> use gigE network connection to the NAS.
> >>
> Our current performance ranges roughly between 20-30MB/s for backups. Some bursts higher
> some slower. We're planning on dual gigE connections to the network for this NAS device.

Do you know fast you can get RMAN to push data off of your server? I mean, if you didn't need to worry about network or NAS disk performance, how fast can you stream off the database? I think the BACKUP VALIDATE command might give that info since it reads the database but doesn't produce output. Anyway, that'll give you an idea of your limits and help keep you from over-engineering your solution.

Hmm, you're more interested in restores. Unless you have a copy of production hardware, you'll probably need to use rule-of-thumb to come up with maximum restore throughput. So far I've seen about 1/2 performance for RMAN restores vice backups. Other DBAs on the list probably have better ideas on what you should expect. (That is to say, I might have had tuning issues and theoretically one can achieve 1:1 ratio...)

It this point I usually sit down with my SAs and get some numbers on expected performance for network and disk throughputs given different configurations.

I'm sure you've already looked at some or all of this. I mention it because I had a system once that just wouldn't go above 15MB/s for anything, cp, RMAN, you name it.

> This is the meat of what I was asking. If we were going to be using this technology as a
> on-line storage for our database, SCSI would have been my main choice. Again, since this NAS device is mainly
> for in-line backups and recovery - I was just curious about the speed factor of SATA technology and would I actually
> speed up my backup and recovery performance or would I just be "substituting" NAS for Tape.

Playing with the numbers from above will let you know if it'll be any speed up for backups/restores. There is another thing to consider. I assume you'll have enough storage to keep at least one full backup on disk. If for whatever reason you need to go back beyond what you have on disk, you'll have both the restore from tape time and then the RMAN recovery from disk time. Yuck.

... crazy PC cheap stuff ...
> >>
> Interesting alternative.
>

I haven't priced anything like this. I wonder how much it would cost and what kind of more traditional backup system you could get for the same money. And how they would compare in terms of performance and capacity.

Let's see, let's go with two systems for redundancy. You can get motherboards that have 2 built-in SATA connections and a gigE port. Cheap cpu, little memory, vanilla box, linux, call the whole thing $500 for round numbers. Newegg (hehe) has a 400 GB SATA drive for $308 (dang, I hoped for under 250). So, $1100 each, $2200. Heck, management might spring for it just to support "research" and the chance that something interesting might result.

...snip...
> >>
> Side note. The last discussion the VP of IT and I had with the VP of Finance
> and mentioned the words "Disaster Recovery", the VP of Finance started to
> "chuckle" to himself. Both the VP of IT and myself saw him. To answer your question
> "Worried about single point of failure - Nope!"

Hehe. Maybe the VP of F will go for the laptop/firewire HD/RAC setup.  "I know production's down. The batteries need to be recharged."

Steven

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