Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Can you post the contents your /proc/drbd?
You might also want to add "no-disk-drain", and see if that helps.
Gordan
Andrew (Anything) wrote:
> Hi All
>
> I've recently started trying to use DRBD + ocfs2 in a dual node setup and
> have had issues with very slow write performance.
>
> Adding no-disk-barrier, no-disk-flushes and no-md-flushes seems to work for
> hundreds of different google results, and sounds like that's why my drbd
> disk is so slow.
>
> So I thought I'd fire up a test on 2 x virtual machines (on physically
> different machines) to test see the sort of change that this might make.
> These two virtual machines are far from super speedy, and are only on
> 100mbit (direct interconnect), but I expected to see at least some sort of
> improvement.
>
> All ive done is add the no flush lines to the disk section of r0 on both
> servers.
> no-disk-barrier;
> no-disk-flushes;
> no-md-flushes;
>
> Theyre currently running v8.2.7, but I checked v8.3.0 aswell as v8.0.14 (on
> an older kernel) just in case. All with pretty much the same results.
>
> I'm hoping someone can see clear as day what ive missed, ive included some
> of my benchmark results.
>
> Thanks in advance.
> Andy..
>
>
> #dd if=/dev/zero of=/dev/sdb bs=512k count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 524288000 bytes (524 MB) copied, 15.0304 seconds, 34.9 MB/s
>
> # dd if=/dev/zero of=/dev/sdb bs=512 count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 512000 bytes (512 kB) copied, 0.351227 seconds, 1.5 MB/s
>
>
> ##### without flushes:
> #single node
> # dd if=/dev/zero of=/dev/drbd0 bs=512k count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 524288000 bytes (524 MB) copied, 15.0428 seconds, 34.9 MB/s
>
> # dd if=/dev/zero of=/dev/drbd0 bs=512 count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 512000 bytes (512 kB) copied, 0.367788 seconds, 1.4 MB/s
>
> #dual node
> # dd if=/dev/zero of=/dev/drbd0 bs=512k count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 524288000 bytes (524 MB) copied, 51.0372 seconds, 10.3 MB/s
>
> # dd if=/dev/zero of=/dev/drbd0 bs=512 count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 512000 bytes (512 kB) copied, 2.03025 seconds, 252 kB/s
>
>
> ##### with flushes:
> #single node
> # dd if=/dev/zero of=/dev/drbd0 bs=512k count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 524288000 bytes (524 MB) copied, 17.5014 seconds, 30.0 MB/s
>
> # dd if=/dev/zero of=/dev/drbd0 bs=512 count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 512000 bytes (512 kB) copied, 0.420332 seconds, 1.2 MB/s
>
> #dual node
> # dd if=/dev/zero of=/dev/drbd0 bs=512k count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 524288000 bytes (524 MB) copied, 49.6752 seconds, 10.6 MB/s
>
> # dd if=/dev/zero of=/dev/drbd0 bs=512 count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 512000 bytes (512 kB) copied, 1.99413 seconds, 257 kB/s
>
>
> # drbdsetup /dev/drbd0 show
> disk {
> size 0s _is_default; # bytes
> on-io-error detach;
> fencing dont-care _is_default;
> no-disk-barrier ;
> no-disk-flushes ;
> no-md-flushes ;
> max-bio-bvecs 0 _is_default;
> }
> ..
> al-extents 1201;
> ..
> sndbuf-size 0; # bytes (larger buffers had slower results for
> small files test)
>
>
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