[DRBD-user] Expected sync speed for a 425gb volume?

Nate Carlson natecars at real-time.com
Wed Apr 6 20:44:11 CEST 2005

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


On Wed, 6 Apr 2005, Todd Denniston wrote:
> Brand new systems, fresh out of the box?

Yeah. Dell boxes, but with 3ware SATA controllers instead of the 
controllers they sell.

> A few quick questions:
>
> 1) have each of the raid 5 arrays gotten finished building themselves?
> The drive arrays I got first required time to do some kind of setup.
> After I told the drive array that it was raid 5, it took ~4 hours and
> the drives were unusable until it was finished.

Yup; I made sure to wait until they were done with that.  :)

> 2) did you know that when you setup drbd against the disks the first
> time it has to do a full sync between the drives to get them to the same
> state, i.e. all 424334M has to be transferred? This could mean your
> mkfs.ext3 is causing the disk to seek between where mkfs is writing and
> where drbd is reading (these might be quite a bit apart) and this slows
> both down. You might try putting the mkfs to sleep and see what the sync
> rate goes to.

I also tried sync'ing without running the mkfs.ext3 on them; it was 
getting better speeds (~15MB/sec), but still not what I'd expect.

I think I've got another problem with the drive array config on both
systems; I'm working on trying to figure that out now.

-- 
Nate Carlson <natecars at real-time.com>   | Phone : (952)943-8700
http://www.real-time.com                | Fax   : (952)943-8500




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