Image Hosting

Dennis Jacobfeuerborn dennisml at conversis.de
Thu Oct 14 21:43:17 MSD 2010 

This looks fairly benign to me. You get lots of random reads so you can 
expect the cpu to wait for i/o occasionally.
One remedy is to spread the data across more disks and the other is to put 
more ram into the machine so more data can be cached.

I have a 30TB system using 48 disks and two controllers here where the I/O 
wait is on average 85% yet it delivers the data with fairly low latency.

You never actually mentioned what your real problem is (you just said "Now 
on we're having problem with disk i/o".)

Regards,
   Dennis

On 10/14/2010 05:05 PM, Indo Php wrote:
> the output of iotop
> Total DISK READ: 15.67 M/s | Total DISK WRITE: 0.00 B/s
>
> the output of vmstat 10 10
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 0 1 31736 3518240 486048 2719488 0 1 646 321 70 39 1 4 88 7
> 0 0 31736 3474616 489792 2763936 0 0 10909 96 12010 2568 1 5 76 17
> 0 0 31736 3428900 492456 2797516 0 0 11062 152 12099 2546 1 6 78 15
> 0 1 31736 3382620 494924 2833764 0 0 12728 136 12709 2580 1 7 76 16
> 0 1 31696 3325956 497404 2872368 4 0 11678 244 12532 2571 2 6 77 15
> 0 0 31696 3288048 500144 2906464 0 0 9947 178 12187 2539 1 6 80 13
> 0 1 31684 3250064 503244 2947148 1 0 10628 166 12279 2613 1 7 78 15
> 0 0 31680 3180800 507244 2995880 0 0 12200 186 12512 2680 1 7 73 19
> 0 0 31680 3126368 510364 3047976 0 0 12083 149 12641 2738 2 6 70 21
> 0 1 31680 3068704 513724 3093616 0 0 11916 176 12648 2799 1 7 74 18
>
>
> ---------------------------------------------------------------------------
> *From:* Dennis Jacobfeuerborn <dennisml at conversis.de>
> *To:* nginx at nginx.org
> *Sent:* Thu, October 14, 2010 9:57:26 PM
> *Subject:* Re: Image Hosting
>
> Please re-run the vmstat as "vmstat 10 10". That should give a better
> glimpse at what the system is doing.
>
> On 10/14/2010 04:26 PM, Indo Php wrote:
>  > Here's the output of "iostat -d 60 2"
>  > Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
>  > sda 85.58 4947.94 2619.30 593632866 314252346
>  >
>  > Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
>  > sda 114.41 8395.93 339.01 503840 20344
>  >
>  > here's the output of vmstat
>  > procs -----------memory---------- ---swap-- -----io---- -system--
> ----cpu----
>  > r b swpd free buff cache si so bi bo in cs us sy id wa
>  > 0 1 332 63136 628344 6085040 0 0 617 324 17 27 1 4 88 6
>  >
>  > ---------------------------------------------------------------------------
>  > *From:* Dennis Jacobfeuerborn <dennisml at conversis.de
> <mailto:dennisml at conversis.de>>
>  > *To:* nginx at nginx.org <mailto:nginx at nginx.org>
>  > *Sent:* Thu, October 14, 2010 7:54:26 PM
>  > *Subject:* Re: Image Hosting
>  >
>  > Ah, sorry I somehow didn't catch that last line with the actual HW setup.
>  >
>  > If my math skills don't fail me (and they very well might) the traffic and
>  > image size data mean that you serve about 300 images per second.
>  > Can you post a few lines of vmstat output and perhaps the output of "iostat
>  > -d 60 2"?
>  >
>  > Also how are the hits distributed across the whole pool of images? Are
>  > these hits truly random or are some images hit significantly more often
>  > than others?
>  >
>  > More ram would obviously take some pressure off the disks if they are
>  > really the problem.
>  >
>  > Regards,
>  > Dennis
>  >
>  > On 10/14/2010 02:26 PM, iptablez at yahoo.com <mailto:iptablez at yahoo.com>
> <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>> wrote:
>  > > Actually the image size is arround 100KB each. The server is running in
>  > 250Mbps traffic.
>  > > I already described the disk I'm using is scsi 15K RPM in raid 0
>  > >
>  > >
>  > > Sent from my BlackBerry®
>  > > powered by Sinyal Kuat INDOSAT
>  > >
>  > > -----Original Message-----
>  > > From: Dennis Jacobfeuerborn<dennisml at conversis.de
> <mailto:dennisml at conversis.de>
>  > <mailto:dennisml at conversis.de <mailto:dennisml at conversis.de>>>
>  > > Date: Thu, 14 Oct 2010 14:23:26
>  > > To:<nginx at nginx.org <mailto:nginx at nginx.org> <mailto:nginx at nginx.org
> <mailto:nginx at nginx.org>>>
>  > > Reply-To: nginx at nginx.org <mailto:nginx at nginx.org>
> <mailto:nginx at nginx.org <mailto:nginx at nginx.org>>
>  > > Subject: Re: Image Hosting
>  > >
>  > > But if those 5,000 req/s each hit a different 1mb image then you need to
>  > > read 5gb of data from you storage which if your storage is just a
> plain old
>  > > sata disk is going to be a huge problem.
>  > >
>  > > Unfortunately Indo Php is not providing nearly enough information to give
>  > > any sort of advice. If he is lucky then putting lots of ram in the machine
>  > > for pagecache can help here if the cache hit ratio is good but if it
> is not
>  > > then he probably has to distribute the I/O across more spindles and go for
>  > > a raid with lots of disks.
>  > >
>  > > Regards,
>  > > Dennis
>  > >
>  > > On 10/14/2010 10:33 AM, SplitIce wrote:
>  > >> Hmm well talking from experience nginx can serve upwards of 5,000
> req/s for
>  > >> static files if configured right. Ill leave this for Igor or someone more
>  > >> expericed to reply to.
>  > >>
>  > >> On Thu, Oct 14, 2010 at 7:28 PM, Indo Php<iptablez at yahoo.com
> <mailto:iptablez at yahoo.com>
>  > <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>>
>  > >> <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>
> <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>>>> wrote:
>  > >>
>  > >> i tried to use AIO, but it seems my server is getting slower
>  > >>
>  > >>
> ---------------------------------------------------------------------------
>  > >> *From:* SplitIce<mat999 at gmail.com <mailto:mat999 at gmail.com>
>  > <mailto:mat999 at gmail.com
> <mailto:mat999 at gmail.com>><mailto:mat999 at gmail.com
> <mailto:mat999 at gmail.com> <mailto:mat999 at gmail.com <mailto:mat999 at gmail.com>>>>
>  > >> *To:* nginx at nginx.org <mailto:nginx at nginx.org>
> <mailto:nginx at nginx.org <mailto:nginx at nginx.org>><mailto:nginx at nginx.org
> <mailto:nginx at nginx.org>
>  > <mailto:nginx at nginx.org <mailto:nginx at nginx.org>>>
>  > >> *Sent:* Thu, October 14, 2010 2:47:55 PM
>  > >> *Subject:* Re: Image Hosting
>  > >>
>  > >> Try any of these:
>  > >> 1) Compile nginx with AIO support
>  > >> 2) Try directio option
>  > >> 3) Try sendfile option
>  > >>
>  > >> On Thu, Oct 14, 2010 at 6:36 PM, Indo Php<iptablez at yahoo.com
> <mailto:iptablez at yahoo.com>
>  > <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>>
>  > >> <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>
> <mailto:iptablez at yahoo.com <mailto:iptablez at yahoo.com>>>> wrote:
>  > >>
>  > >> hi there,
>  > >>
>  > >> we have an image hosting, and of course we're using Nginx!
>  > >>
>  > >> Now on we're having problem with disk i/o. With 200GB of images.
>  > >> Is there any recommendation for this matter? Nginx configuration or
>  > >> Hardware/other software configuration?
>  > >>
>  > >> We already used Dual Quad Core 3Ghz, 8 GB RAM, 6x73GB 15k SCSI server
>  > >>
>  > >>
>  > >>
>  > >>
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>  > >>
>  > >>
>  > >>
>  > >> --
>  >> > Warez Scene<http://thewarezscene.org> Free Rapidshare Downloads
>  >> > <http://www.nexusddl.com>
>  > >>
>  > >>
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