[DRBD-user] Better performance with meta-data at the beginning of the device?

Diego Julian Remolina diego.remolina at ibb.gatech.edu
Wed Sep 13 19:05:16 CEST 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


>>This does not seem to make sense; the inner tracks have lower performance 
>>because the linear speed is slower there and the amount of data you can 
>>store is less. 
> 
> 
> what about seeks ?

And to make things even harder to figure out, how about the effect of NCQ on seeks and performance?

I guess there are way too many factors to know for sure other than performing benchmarks. If your 
hard drive is not totally full, then most of the reads and writes occur in the outter edges, right? 
so then, what would possibly make more sense to lower seek times and increase performance is to 
create an external metadata partition before and the drbd partition later. Something like this:

/dev/sda1 /boot
/dev/sda2 /
/dev/sda3 /var
extended
/dev/sda5 unformated for metadata (Allow 128MB per drbd partition)
/dev/sda6 drbd0

How does that look?

Personally, I have two servers with 12 Drives in raid 10 using the ARECA ARC-1160 raid controllers. 
Running benchmarks with drbd on those servers I found the bottleneck to be the Gigabit card. Bonnie 
maxed out at ~120MB/s using drbd while I got ~230MB/s without drbd (no need to channel bond, I am 
happy with 120MB/s writes), so even having the metadata at the end of the disk does not matter that 
much on my systems. I am not sure it would make such a big difference in a 1 hard disk system either.

My Storage benchmarks page in case you are interested: 
https://services.ibb.gatech.edu/wiki/index.php/Benchmarks:Storage

Diego

> 
> Regards,
> Paddy



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