Hello,
I tried CFQ/deadline schedulers, when I run the following:
# /usr/bin/time dd if=/dev/sdb2 of=/raid6/sdb2.img
Behind which are 2 x Raptor 150GB disks, the system is pretty much unusable
when I control-c the dd, it comes back to life.
The RAID-6 is a 15-disk RAID-6 which does 600-700MB/s writes.
All cards are on PCI-e and have adequate bandwidth on a P55 board (DP55KG).
Are there any recommended tuning options for a RAID-1 configuration, such that
a heavy I/O read or write operation does not pause the system?
During the dd..
Drive Performance Monitor Configuration for /c1 ...
Performance Monitor: ON
Version: 1
Max commands for averaging: 100
Max latency commands to save: 10
Requested data: Instantaneous Drive Statistics
Queue Xfer Resp
Port Status Unit Depth IOPs Rate(MB/s) Time(ms)
------------------------------------------------------------------------
p0 OK u0 25 762 26.219 19
p1 OK u0 23 780 25.953 24
p2 OK u1 1 0 0.000 98
p3 NOT-PRESENT - - - - -
Justin.
Justin,
Can you try turning down the queue depth of the disk that is getting
written to to see if that resolves your responsiveness issue?
I.E.: echo "16" > /sys/block/sdX/device/queue_depth
(replace X with disk letter of device from /raid6 mountpoint).
FYI: It's probably better to send questions like this to linux-scsi rather
than linux-kernel.
-Adam
On Fri, Oct 16, 2009 at 2:46 PM, Justin Piszcz <[email protected]> wrote:
> Hello,
>
> I tried CFQ/deadline schedulers, when I run the following:
>
> # /usr/bin/time dd if=/dev/sdb2 of=/raid6/sdb2.img
>
> Behind which are 2 x Raptor 150GB disks, the system is pretty much unusable
> when I control-c the dd, it comes back to life.
>
> The RAID-6 is a 15-disk RAID-6 which does 600-700MB/s writes.
>
> All cards are on PCI-e and have adequate bandwidth on a P55 board (DP55KG).
>
> Are there any recommended tuning options for a RAID-1 configuration, such
> that
> a heavy I/O read or write operation does not pause the system?
>
> During the dd..
>
> Drive Performance Monitor Configuration for /c1 ...
> Performance Monitor: ON
> Version: 1
> Max commands for averaging: 100
> Max latency commands to save: 10
> Requested data: Instantaneous Drive Statistics
>
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Queue ? ? ? ? ? Xfer ? ? ? ? Resp
> Port ? Status ? ? ? ? ? Unit ? Depth ? IOPs ? ?Rate(MB/s) ? Time(ms)
> ------------------------------------------------------------------------
> p0 ? ? OK ? ? ? ? ? ? ? u0 ? ? 25 ? ? ?762 ? ? 26.219 ? ? ? 19 p1 ? ? OK
> ? ? ? ? ? u0 ? ? 23 ? ? ?780 ? ? 25.953 ? ? ? 24 p2 ? ? OK ? ? ? ? ? ? ? u1
> ? ? 1 ? ? ? 0 ? ? ? 0.000 ? ? ? ?98 p3 ? ? NOT-PRESENT ? ? ?- ? ? ?- ? ? ? -
> ? ? ? - ? ? ? ? ? ?-
>
> Justin.
>
>
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On Fri, 16 Oct 2009, adam radford wrote:
> Justin,
>
> Can you try turning down the queue depth of the disk that is getting
> written to to see if that resolves your responsiveness issue?
>
> I.E.: echo "16" > /sys/block/sdX/device/queue_depth
>
> (replace X with disk letter of device from /raid6 mountpoint).
>
> FYI: It's probably better to send questions like this to linux-scsi rather
> than linux-kernel.
>
> -Adam
>
Hi,
Will do in the future for related queries, I set it to 16, its almost usable,
I set it to 8-- both are a bit slow during a dd read but at least it does not
starve processes anymore to the point of failure, e.g.:
Oct 16 18:17:18 p34 amavis[12685]: (12685-10) (!)SA TIMED OUT, backtrace: at /usr/share/perl5/Mail/SpamAssassin/BayesStore/DBM.pm line 1855\n\teval {...} called at /usr/share/perl5/Mail/SpamAssassin/BayesStore/DBM.pm line 1855\n\tMail::SpamAssassin::BayesStore::DBM::tok_unpack('Mail::SpamAssassin::BayesStore::DBM=HASH(0x4bf2400)', '\\x{0}\\x{97}\\x{0}\\x{0}\\x{0}\\x{e2}\\x{3}\\x{0}\\x{0}k\\x{af}\\x{d8}J') called at /usr/share/perl5/Mail/SpamAssassin/BayesStore/DBM.pm line 865\n\tMail::SpamAssassin::BayesStore::DBM::tok_get_all('Mail::SpamAssassin::BayesStore::DBM=HASH(0x4bf2400)', '\\x{e5}a\\x{96}\\x{ce} ', '\\x{b3}]\\x{5}\\x{13}\\x{dd}', 'd\\x{b7}\\x{88}\\x{f2}%', '\\x{da}\\x{1}\\x{d4}/T', '\\x{fe}\\x{18}\\x{c6}\\x{d0}_', 'J\\x{9}\\x{9b}\\x{9a} ', 'l\\x{ce}p\\x{92}Y', '\\x{b8}\\x{8e}\\x{cc}z\\x{b3}', ...) called at /usr/share/perl5/Mail/SpamAssassin/Bayes.pm line 1185\n\tMail::SpamAssassin::Bayes::scan('Mail::SpamAssassin::Bayes=HASH(0x214b4e0)', 'Mail::SpamAssassin::PerMsgS
t[...]
Thank you!
Justin.