Re: [Networker] Slightly off-topic query
Thanks for your answers!
Stan Horwitz wrote:
> I am not sure, but your environment is crying out for a block-level
> disk-to-disk backup solution.
Block level? Do you mean rawasm?
Anyway, disk-to-disk-to-tape is what we are doing here, so network
throughput would not be the major issue. But when we stage to tape we must
ensure that all tape drives are fed with enough data.
Jeff Mery wrote:
Let's say I just have one LTO2 drive doing Windows backups: 30MB/sec
native * 1.5 compression = 45MB/sec; add 6.75 MB for safety net (round to
7MB) and we have 52MB/sec that I need to push to this drive. If this
drive is doing Oracle, I would have (30MB/sec * 3 compression) = 90MB/sec;
add 15 MB for safety net and we have 105MB/sec. Does that seem high for a
30MB/sec device? Absolutely. Remember that the native drive speed is the
fastest that the heads can put data onto the media - period. At 3:1
compression, I need to push 90MB of data to keep the drive at 30MB =).
Hmm... I think we should keep the old server and get a new disk array. 30-45
MB/s is the usual maximum that I have seen on the LTO2 drive since now (we
have it for 3 weeks now). When other drives are staging too, it drops to
Just because you have 2Gb FC coming in, doesn't mean
you'll be able to push that through SCSI on the other end. This is
especially true when mixing drive types as the entire SCSI channel will
drop to the speed of the slowest device.
Oh, so all four drives would be connected to a single SCSI channel? I
thought that each connector on such a bridge would be an isolated SCSI channel.
I would also recommend dedicating one FC card/port for tape and a second
one for disk.
Finally, be sure this 1U server has the horsepower to move all this data.
They don't in our environment so we have to use 4 CPU systems.
*sigh* I'll have to ask my boss for all this... it will be quite expensive.
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