asterisk users - Apr 2006 - update - 512 Simultaneous Calls with Digital Recording

Hi All,

 

In previous mail lists, people talked about a solution to record large
amount of simultaneous calls. And then it seems that RAM disk solution
was the best choice due to the I/O bottleneck of Hard disk (System).
Please find the previous discussion as follows:

http://lists.digium.com/pipermail/asterisk-users/2005-October/120930.htm
l

 

http://thread.gmane.org/gmane.comp.telephony.pbx.asterisk.user/118497

 

I noticed that an Intel server platform comes with 4 ports SATA-II
RAID0/1 controller. Please check this link:

http://developer.intel.com/design/servers/boards/se7230nh1-e/index.htm

SATA-II is 3Gps I/O. so I am thinking implement this solution for
recording large amount of simultaneous calls. My proposed solution is:

 

CPU: Prentium 4 Dual core 3.2G or higher

RAM: 2G or more

OS HDD: 2 x 80G SATA-II HDD for RAID 1 (for OS)

Separate HDD for voice recording: 1 x 200G SATA-II HDD standalone

Voice recording format: WAV

 

I did a test on my Asterisk PBX. One leg of 61 seconds WAV voice
recording use 947564 bytes of hard disk. I did an optimal estimate of
numbers of simultaneous calls with 3Gps without thinking of CPU and
system limitation.

 

Two legs: 947564 x 2 x 8 = 1895128 Bytes x 8 = 15161024 bits

 

15161024/61 = 248541 bits/s

 

So the number of simultaneous calls 3Gps I/O can handle:

 

3(Gps) x 1024(Mb/G) x 1024 (Kb/M) x 1024 (b/Kb) / 248541 = 12960 calls.

 

512 are far less than 12960. So I think the hard disk I/O should not
have any bottleneck problem for 512 simultaneous calls.

 

Welcome to add your comments, do test and give feedback.

 

Cheers,

Isaac Xiao

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Hello,

What happens a few weeks into this when you've fragmented the free
space on the drives by deleting files periodically and rewriting in
some places? The consistent performance of SATA drives goes down
dramatically when this happens, much more so than on a SCSI-based
drive system.

Also, you don't seem to take into account the read-write-seek time of
SATA drives into your calculations

Another thing to consider is that if anything else is being done on
these drives(like running Linux or Asterisk or anything else) the
write performance will also be effected.

MATT---

On 4/3/06, Isaac Xiao <isaac.x@kvbkunlun.com>
wrote:
>
>
>
> Hi All,
>
>
>
> In previous mail lists, people talked about a solution to record large
> amount of simultaneous calls. And then it seems that RAM disk solution was
> the best choice due to the I/O bottleneck of Hard disk (System). Please
find
> the previous discussion as follows:
>
> http://lists.digium.com/pipermail/asterisk-users/2005-October/120930.html
>
>
>
> http://thread.gmane.org/gmane.comp.telephony.pbx.asterisk.user/118497
>
>
>
> I noticed that an Intel server platform comes with 4 ports SATA-II RAID0/1
> controller. Please check this link:
>
> http://developer.intel.com/design/servers/boards/se7230nh1-e/index.htm
>
> SATA-II is 3Gps I/O. so I am thinking implement this solution for recording
> large amount of simultaneous calls. My proposed solution is:
>
>
>
> CPU: Prentium 4 Dual core 3.2G or higher
>
> RAM: 2G or more
>
> OS HDD: 2 x 80G SATA-II HDD for RAID 1 (for OS)
>
> Separate HDD for voice recording: 1 x 200G SATA-II HDD standalone
>
> Voice recording format: WAV
>
>
>
> I did a test on my Asterisk PBX. One leg of 61 seconds WAV voice recording
> use 947564 bytes of hard disk. I did an optimal estimate of numbers of
> simultaneous calls with 3Gps without thinking of CPU and system limitation.
>
>
>
> Two legs: 947564 x 2 x 8 = 1895128 Bytes x 8 = 15161024 bits
>
>
>
> 15161024/61 = 248541 bits/s
>
>
>
> So the number of simultaneous calls 3Gps I/O can handle:
>
>
>
> 3(Gps) x 1024(Mb/G) x 1024 (Kb/M) x 1024 (b/Kb) / 248541 = 12960 calls.
>
>
>
> 512 are far less than 12960. So I think the hard disk I/O should not have
> any bottleneck problem for 512 simultaneous calls.
>
>
>
> Welcome to add your comments, do test and give feedback.
>
>
>
> Cheers,
>
> Isaac Xiao
> _______________________________________________
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>
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> To UNSUBSCRIBE or update options visit:
>
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>
>
>

Matthew, thanks for your feedback and advice.
> what I actually experienced was the complete breakdown of Asterisk at 
> around 60 concurrent recordings without it (the reality).
The drive for saving your voice recordings is the same as your OS
(Asterisk)? What do you think that save the voice recordings to a
dedicated drive rather than the one which Asterisk program (OS) locates?
I also think about using GSM format (Monitor(gsm,${CALLFILENAME}, mb))
rather than WAV, PCM. In this case, it will use more CPU, but I/O of
hard disk is reduced dramatically as you mentioned that it is I/O
bottleneck issue, not CPU (In my case, I want to use P4 Dual core CPU or
extreme edition). In order to reduce the CPU usage, we can have two leg
files mixed after peak time.

Matt mentioned about fragmented free space. I googled about Linux
defragment topic. People always talk about that Linux doesn't need to
defragment, it can handle it by itself very well. Not sure how true it
is.

I am looking a solution to record expanding simultaneous calls in the
future in a call centre which accepts calls from our global branches. If
I find the good solution, I definitely post it to the community.

Cheers,
Isaac Xiao