[DRBD-user] Multi-threaded on-line verification

Lars Ellenberg lars.ellenberg at linbit.com
Tue Apr 22 14:40:59 CEST 2014

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

On Mon, Apr 21, 2014 at 11:11:09AM +0200, Ben RUBSON wrote:
> Hello,
> Let's assume that we have a resource which contains several volumes.
> When an on-line verification is launched, all volumes are verified
> together, but it seems that the job is made by only one thread.
> The bottleneck in the on-line verification are not the disks, but the
> CPU, as it must deal with many (for example) crc32c operations.
> So my question is, could we think about an implementation which would
> start one verification thread for each volume ?
> It would dramatically speed-up on-line verification (for my own case,
> with 4 volumes in 1 resource, it would decrease verification time from
> 56 hours to 14 hours).

iirc, when we implemented it, the kernel crypto api was supposed
to get asynchronous hash support "soon", so we did not bother to add our
own threading/async layer over this.

Guess that "soon" is very relative.

Yes, we can add that as feature request
somewhere on our (not so short) todo list.

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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