Re: Sync rates?

[<me@heyjay.com>]

Cable problems, I suspect this is more to ones liking?

platinum:/mnt/config# ./ddtest

time dd if=/dev/hda of=/dev/null bs=64k count=10000
10000+0 records in
10000+0 records out
655360000 bytes transferred in 12.050804 seconds (54383093 bytes/sec)

real    0m12.058s
user    0m0.000s
sys     0m1.780s
time dd if=/dev/hdc of=/dev/null bs=64k count=10000
10000+0 records in
10000+0 records out
655360000 bytes transferred in 11.508676 seconds (56944865 bytes/sec)

real    0m11.510s
user    0m0.010s
sys     0m1.670s


What exactly am I testing here though?  I'm only testing write speed not
read speed, correct?  Is there an analogous test for reads?

Thanks
Jay

----- Original Message ----- 
From: "Guy" <bugzilla@watkins-home.com>
To: <me@heyjay.com>
Sent: Friday, May 07, 2004 1:24 AM
Subject: RE: Sync rates?


> I don't understand what's wrong with your disks.  If you can, configure
one
> as a master without a slave.  Then time it.
>
> My disks are slow/old SCSI disks.  The max speed is about 19Meg/second.
> Today's disks are much faster.
> The reason my disks are as slow as 4000-5000K /sec is that I have 7 of
them
> on a 40M/sec SCSI bus.
> I checked my notes, the speed is just over 5000K/sec.
> If I were to upgrade the SCSI card to a LVD (80M/sec) I would get about
> 10000K/sec.  I did that once with a barrowed card.  Was very cool.
> My disks are Seagate ST118202LC or SX118282LS, depending on where I look!
> 18Gig, 10,000RPM.  Good seek time, but slow sustained transfer rate.
>
> Guy
>
> -----Original Message-----
> From: me@heyjay.com [mailto:me@heyjay.com]
> Sent: Friday, May 07, 2004 1:29 AM
> To: Guy; linux-raid@vger.kernel.org
> Subject: Re: Sync rates?
>
> Weird, seems as if the faster the processor the longer the test takes.  I
> ran it on 2 other machines, in addition to the one with raid.  Here are
the
> results.  What type of disks are you using?  Your results are almost twice
> as fast as my fastest (which is machine 3 i.e. my slowest chip speed).
>
> Jay
>
> Machine 1 (the one in question), AMD 3200, 1 GB RAM, Disks on individual
IDE
> channels
> platinum:~# df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/md0              19686680   1195512  17491132   7% /
> tmpfs                   452284         0    452284   0% /dev/shm
> /dev/md1              39373624     32844  37340696   1% /opt
> /dev/md2              39373624     32848  37340692   1% /home
> /dev/md4              14974680     32872  14181136   1% /usr/local
>
> platinum:~# time dd if=/dev/hda of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 166.335481 seconds (3939989 bytes/sec)
>
> real    2m46.336s
> user    0m0.004s
> sys     2m13.280s
>
>
> platinum:~# time dd if=/dev/hdc of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 171.632623 seconds (3818388 bytes/sec)
>
> real    2m51.634s
> user    0m0.004s
> sys     1m33.162s
>
> # Machine 2, PII 400 Mhz, the disks are master/slave
> meir:~# df
> Filesystem           1k-blocks      Used Available Use% Mounted on
> /dev/hda4              4806936   1220040   3342708  27% /
> /dev/hda1                46636       935     43293   3% /boot
> /dev/hda5              4996728    938156   3804748  20% /home
> /dev/hda6              3937220   2026628   1710588  55% /usr
> /dev/hdb2              9843308   8246848   1096440  89% /opt
> au:/usr/local/src     29530400   6731216  21299120  25% /usr/local/src
>
> meir:~# time dd if=/dev/hda of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
>
> real    2m48.300s
> user    0m0.030s
> sys     1m49.000s
>
> Machine 1, PPro 180 Mhz, Master/Slave
> abba:~# df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/hda1              9851308   2534948   6815940  28% /
> tmpfs                   258204         0    258204   0% /dev/shm
> /dev/hda3              7842996   3502032   3942552  48% /mnt/hda3
>
>
> abba:~# time dd if=/dev/hda of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 56.396242 seconds (11620632 bytes/sec)
>
> real    0m56.416s
> user    0m0.120s
> sys     0m11.960s
>
>
>
> ----- Original Message ----- 
> From: "Guy" <bugzilla@watkins-home.com>
> To: <me@heyjay.com>
> Sent: Thursday, May 06, 2004 9:44 PM
> Subject: RE: Sync rates?
>
>
> > My system re-builds at 4000-5000K/sec/disk.  It has 14 disks.
> > During a re-build the CPU load is below 5%.
> > I have 2 CPUs, P3-500Mhz, 512Meg ram.
> > During a re-build I don't notice any slowdown.  I had a disk fail and it
> > re-build on the spare.  I did not know until hours after it was done.
> >
> > If you cat /proc/mdstat it will show the re-build rate.
> > That rate is per disk, not an overall total.
> >
> > I would say your system has problems!
> > Test each disk with dd.
> > This is a read test!!
> >
> > time dd if=/dev/hda of=/dev/null bs=64k count=10000
> >
> > This should take less than a minute (34.6 seconds for me).
> > If the above gives the same results on each disk, drop the count=10000.
> >
> > time dd if=/dev/hda of=/dev/null bs=64k
> >
> > Without the count=10000 it will read 100% of the disk, this may take an
> hour
> > or more.
> > It will report a record count.
> > Do this math to determine the speed in K per second.
> > Records*64/number of seconds
> >
> > Replace "hda" with whatever is correct for you.
> > Do this for each disk.
> > I bet you find 1 disk is much slower than the others.
> > Maybe a bad cable, don't know.
> >
> > Good luck,
> > Guy
> >
> > -----Original Message-----
> > From: linux-raid-owner@vger.kernel.org
> > [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of me@heyjay.com
> > Sent: Thursday, May 06, 2004 10:02 PM
> > To: Paul Clements
> > Cc: linux-raid@vger.kernel.org
> > Subject: Re: Sync rates?
> >
> > My machine was idle during the rebuild.  When I say idle, I mean no one
> > logged in, no user processes running (except me sshed into the box), no
> > database, no I/O other than the rebuild.
> >
> > While the rebuild was going on my system was debilitated, totally slow
to
> > respond to ssh commands
> >
> > Jay
> > ----- Original Message ----- 
> > From: "Paul Clements" <paul.clements@steeleye.com>
> > To: <me@heyjay.com>
> > Cc: <linux-raid@vger.kernel.org>
> > Sent: Thursday, May 06, 2004 2:59 PM
> > Subject: Re: Sync rates?
> >
> >
> > > me@heyjay.com wrote:
> > >
> > > > platinum:~# cat /proc/sys/dev/raid/speed_limit_min
> > > > 1000
> > > > platinum:~# cat /proc/sys/dev/raid/speed_limit_max
> > > > 200000
> > >  > Are these acceptable?
> > >
> > > Well, those values are in KB/s. And, your resync rate is about:
> > >
> > > 120000000 / ( 24 * 60 * 60 ) = 1388 KB/s
> > >
> > > if my calculations are correct. I'd try bumping the min value up to
say
> > > 10000 and see if that speeds things up. Is there much I/O activity on
> > > the system? That will slow down a resync quite a bit, too.
> > >
> > > --
> > > Paul
> > >
> > >
> >
> > -
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> >
> >
> >
> >
>
>
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