[DRBD-user] write performance for DRBD devices seems to be slow

Warren Beldad advisory22 at gmail.com
Thu Aug 4 04:52:55 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.


what I mean here for my "raw device" is the drbd device.
the /dev/drbd0 which is mounted on /mnt/temp and do an IO test on that
mount point. I should be careful next time :-))
I have here also attached my results with Bonnie++

Sequential Output Per Char using putc(): drbd performs lower:  58.11%
Sequential Output Block using write(2): drbd performs lower:  61.24%
Sequential Output Rewrite: drbd performs lower:  6.19%

thanks, 
warren
 
On 7/21/05, Roger Tsang <perj8 at hotmail.com> wrote:
> Don't use the -o switch.
> 
> >
> >Here is my new results with both max-buffers and max-epoch-size set to
> >maximum. If i was right this is:
> >max-buffers 131072;
> >max-epoch-size 20000;
> >
> >File size set to 4096 KB
> >       Record Size 4 KB
> >       SYNC Mode.
> >       Include fsync in write timing
> >       Include close in write timing
> >       Command line used: ./iozone -s4m -r4k -o -e -c
> >       Output is in Kbytes/sec
> >       Time Resolution = 0.000001 seconds.
> >       Processor cache size set to 1024 Kbytes.
> >       Processor cache line size set to 32 bytes.
> >       File stride size set to 17 * record size.
> >
> >KB  reclen   write rewrite    read      reread    read        write
> >read      rewrite    read         fwrite     frewrite          fread
> >                   freread
> >4096   4       680    5126   598212   590718  518354    2568   520067
> >   4272  520464     9865       9076          1144118
> >1204691
> >
> >Seems nothings has changed. These two parameters, max-buffer and
> >max-epoch-size is under the net section which as i understand is for
> >the network configurations, based on the manual, the size of the tcp
> >socket send buffer, etc. I think this may not affect the performance
> >on the raw device if i am right. I am looking for any tuning
> >parameters (for the raw device) but it seems there are none.
> >thanks,
> >warren
> >
> >On 7/13/05, Diego Julian Remolina <dijuremo at ibb.gatech.edu> wrote:
> > > If you were looking for standard benchmarks, you should probably try
> >bonnie++
> > > from: http://www.coker.com.au/bonnie++/
> > >
> > > Here is the link to the readme file that explains how the tests done and
> >how the
> > > reads and writes are performed.
> > >
> > > http://www.coker.com.au/bonnie++/readme.html
> > >
> > > I am also attaching a file with my results of running bonnie++ on top of
> >an
> > > Areca ARC-1160 PCI-X to SATA raid controller.  I run a total of 15
> >disks, 2 HDD
> > > mirrored for the OS, 12 in raid 10 for storage and have 1 Hot spare.
> > >
> > > I have 1.5 TB of storage on my raid10 array, but I had that split in two
> > > partitions, part1 which is 1TB and part2 which is the rest.  I have only
> > > performed tests for part1.  I ran bonnie++ 3 times and took the average
> >of the 3
> > > runs on the hard drive on both, the raw device and then on the drbd
> >device.
> > > Here is the comparisson:
> > >
> > > Sequential Output Per Char using putc():  drbd performs lower:  5.54%
> > > Sequential Output Block using write(2):   drbd performs lower: 46.49%
> > > Sequential Output Rewrite:                drbd performs lower: 23.99%
> > >
> > > However, keep in mind that with drbd, I am still getting
> > > 47MB/s per char, 123MB/s on block and 65MB/s on rewrites, which is still
> >pretty
> > > good.
> > >
> > > All tests were performed using ext3 with write-back caching enabled on
> >the Areca
> > > raid controller. The test machine has dual Opterons 270 and 4 GB of ram
> >(that is
> > > why the file test size is 8GB) running on RHEL4.
> > >
> > > Here is a link to another page where bonnie++ was used to compare raid 5
> >vs
> > > raid10 but no drbd is involved, you may want to use those results for
> >reference.
> > >
> > > http://johnleach.co.uk/documents/benchmarks/raidperf.html
> > >
> > > Diego
> > >
> > > Quoting Roger Tsang <perj8 at hotmail.com>:
> > >
> > > > Try increasing your max-buffers and max-epoch-size to MAX.
> > > >
> > > >
> > > > >To: drbd-user at lists.linbit.com
> > > > >Subject: Re: [DRBD-user] write performance for DRBD devices seems to
> >be
> > > > >slow
> > > > >Date: Tue, 12 Jul 2005 19:27:29 +0800
> > > > >
> > > > >ok I have here added my iozone results.
> > > > >I am just new to this drbd maybe a month or two. Does anyone have the
> > > > >standard benchmark results for drbd or where can i find it? I am
> > > > >really worried about the write performance on our drbd, the
> >difference
> > > > >is just too big and much more is if it is now under NFS and samba.
> > > > >
> > > > >LVM2 + XFS
> > > > >File size set to 4096 KB
> > > > >     Record Size 4 KB
> > > > >     SYNC Mode.
> > > > >     Include fsync in write timing
> > > > >     Include close in write timing
> > > > >     Command line used: ./iozone -s4m -r4k -o -e -c
> > > > >     Output is in Kbytes/sec
> > > > >     Time Resolution = 0.000001 seconds.
> > > > >     Processor cache size set to 1024 Kbytes.
> > > > >     Processor cache line size set to 32 bytes.
> > > > >     File stride size set to 17 * record size.
> > > > >                                                             random
> > > > >random    bkwd  record  stride
> > > > >               KB  reclen   write rewrite    read    reread    read
> > > > >write    read rewrite    read   fwrite frewrite   fread  freread
> > > > >             4096       4   11680   35386  1126176  1158032  926910
> > > > >34997  939673   35074  907599    64502    68108 1016369  1079917
> > > > >
> > > > >LVM2 + DRBD + XFS
> > > > >File size set to 4096 KB
> > > > >     Record Size 4 KB
> > > > >     SYNC Mode.
> > > > >     Include fsync in write timing
> > > > >     Include close in write timing
> > > > >     Command line used: ./iozone -s4m -r4k -o -e -c
> > > > >     Output is in Kbytes/sec
> > > > >     Time Resolution = 0.000001 seconds.
> > > > >     Processor cache size set to 1024 Kbytes.
> > > > >     Processor cache line size set to 32 bytes.
> > > > >     File stride size set to 17 * record size.
> > > > >                                                             random
> > > > >random    bkwd  record  stride
> > > > >               KB  reclen   write rewrite    read    reread    read
> > > > >write    read rewrite    read   fwrite frewrite   fread  freread
> > > > >             4096       4     619    5138   520068   516903  460170
> > > > >2494  459762    4503  461883    10358     9790 1021212  1003702
> > > > >
> > > > >thanks, warren
> > > > >
> > > > >On 7/8/05, Lars Ellenberg <Lars.Ellenberg at linbit.com> wrote:
> > > > > > / 2005-07-07 20:18:06 +0800
> > > > > > \ Warren Beldad:
> > > > > > > Hi all!
> > > > > > >
> > > > > > > I have are a simple results of the performance of my drbd test
> > > > >machines.
> > > > > > > Using the dd command, first I get the performance value of my
> > > > > > > harddisk. That would be formatting the /dev/sda with XFS and
> >then
> > > > > > > mount it and then write a 1GB file (which is twice the size of
> >my RAM)
> > > > > > > into that disk with dd command on different block sizes and then
> >read
> > > > > > > back that file into the black hole.
> > > > > > > time dd if=/dev/zero of=testfile.txt bs=512k count=2000
> > > > > > > time dd if=testfile.txt of=/dev/null bs=512k
> > > > > >
> > > > > > your benchmark is broken.
> > > > > > man close
> > > > > > man fsync
> > > > > > no, dd does not do fsync.
> > > > > >
> > > > > > --
> > > > > > : Lars Ellenberg                                  Tel
> >+43-1-8178292-0  :
> > > > > > : LINBIT Information Technologies GmbH            Fax
> >+43-1-8178292-82 :
> > > > > > : Schoenbrunner Str. 244, A-1120 Vienna/Europe
> >http://www.linbit.com :
> > > > > > __
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