Hi Bernd,
On Thu, 2010-09-02 at 23:41 +0200, Bernd Schubert wrote:> On Thursday, September 02, 2010, Frank Heckes wrote:
> > Hi all,
> >
> > for some of our OSSes a massive amount of errors like:
> >
> > Sep 2 20:28:15 jf61o02 kernel: blk_rq_check_limits: over max size
> > limit.
> >
> > appearing in /var/log/messages (and dmesg). Does anyone have got a
clue
> > how-to get of the root cause? Many thanks in advance.
>
> linux/block/blk-core.c
>
> int blk_rq_check_limits(struct request_queue *q, struct request *rq)
> {
> if (rq->cmd_flags & REQ_DISCARD)
> return 0;
>
> if (blk_rq_sectors(rq) > queue_max_sectors(q) ||
> blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) {
> printk(KERN_ERR "%s: over max size limit.\n",
__func__);
> return -EIO;
> }
>
>
> I haven''t seen that before, but if I should guess, I would guess
that dm-* has
> a larger queue than your underlying block device. If that is with your DDN
> storage, can you verify if all those devices are have max_sec_kb tuned to
> maximum?
>
Yes, we''re using multipath to access the ''disks''
(luns). Indeed the
setting for ''max_sec_kb'' was different for the multipath
device and disk
devices file, due to an obsolete udev-rule. We changed the values
consistently and the error messages stopped almost immediately. Many
thanks for the help.
> Also, does that come up with 1.8.4 only? (I have SG_ALL in my mind which
was
> increased from 255 to 256, which might not be supported by all scsi host
> adapters).
>
We use version 1.8.1.1 still, but good to know about this.
>
> Cheers,
> Bernd
>
Cheers
-Frank
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