Re: 3ware 9650SE-4PML RAID-1 Question: One reader process starves I/O to the rest of the system?

[Justin Piszcz <jpiszcz@lucidpixels.com>]

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.