[Asterisk-Users] Hard drive write cache
shadowym
shadowym at hotmail.com
Tue Jun 13 15:52:20 MST 2006
You still need a hard drive to run FreePBX as far as I know. Either that
or burn out your 2GB CF drive after a couple months of constant writes. I
would assume Apache and MySQL would need to go on the HD. Voicemail can go
there as well. Linux/Asterisk binaries and base config files can probably
go on the CF read only. Would this work?
Are there any how-to's around that have done something like this? It is
starting to make a bit more sense to me to do it this way but I'm no expert.
If I did it this way I would not have a need for RAID so it will probably
come out to about the same price.
> -----Original Message-----
> From: Nicholas Kathmann
> [mailto:nicholas.kathmann at kathmannconsulting.com]
> Sent: Tuesday, June 13, 2006 1:22 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Hard drive write cache
>
> They have IDE and even some SATA (not easily available) flash
> drives also, some of which are over 80GB. The more space you
> get, the quicker it goes up in price with the larger models
> costing more than most servers. If you want, you can also
> use an IDE to CF adapter.
>
> For the locking plugs, google NEMA-L5 or NEMA-L6 and that
> will show you what they look like. They are readily
> available in most hardware stores for low cost. On the
> server side, you can tie wrap the power cable to the rail or
> something like that, but I would suggest just getting a
> server that has the thumbscrew and clamp to hold the power
> cord in place. They are available on most IBM servers. If
> the power cord is mounted to the wall with staples or those
> nail in C clamps, someone would have to go out of their way
> to pull the power cord out.
>
> Another option if it's a really small installation is to use
> a mini-itx fanless system. We have 2 set up here (in a test
> lab for now) with 1Ghz Via processors running up to ten
> (that's all we've tried) concurrent calls with no problems.
> These is no transcoding and echo cancellation running on
> these. Next it to try some Digium and Sangoma PCI cards in
> them and see how they work. I'll post the results when we
> finish. Such systems are extremely reliable as long as you
> don't pull too much from the small power supplies, etc.
> Regardless of what you use or what you do, trying to achieve
> 5 nines reliability is going to require a whole rack full of
> systems, storage, batteries, etc and a whole lot of
> configuration and testing. Even PBX systems (not all)
> require downtime for firmware upgrades, etc. Most people
> don't bother since the systems aren't connected to data networks.
>
> It was actually easier to pull the power cables out of some
> of the PBX equipment (such as the Definity G3si) than it is
> to pull the equipment out of the Cisco VoIP or IBM servers
> combined with the right PDUs, etc.
>
> Thanks,
> Nick
>
> shadowym wrote:
> > Thanks for the suggestions.
> >
> > CF is not an option for FreePBX which is a requirement for the
> > installs I have in mind. Astlinux on CF is a great option
> otherwise.
> > That is by far the simplest, cheapest, and suprisingly most
> reliable
> > solution I have come across so far. If there was a half
> decent (open
> > source) GUI that could run on Astlinux on CF it would be a
> no brainer IMHO.
> >
> > Physically locking down the server is not an option. It
> will be hung
> > on the wall in place of where a traditional PBX would normally go.
> > This is a telecom closet NOT a server rack environment.
> UPS with auto
> > shut down is just one link in the chain. Do you have any further
> > information of locking plugs? I have not come across those
> before.
> > Of course in order for that to make sense I would need
> locking plugs
> > on both the server AND UPS end. It has to be idiot proof.
> >
> > Think PBX and/or network appliance not computer server. They are
> > idiot proof so it is quite reasonable IMHO to expect the
> same from an
> > Asterisk server (or in my way of thinking, Asterisk network
> appliance).
> >
> >
> >> -----Original Message-----
> >> From: Nicholas Kathmann
> >> [mailto:nicholas.kathmann at kathmannconsulting.com]
> >> Sent: Tuesday, June 13, 2006 11:04 AM
> >> To: Asterisk Users Mailing List - Non-Commercial Discussion
> >> Subject: Re: [Asterisk-Users] Hard drive write cache
> >>
> >> If all you are worried about is the write cache on the
> disks, why not
> >> just put the system on a UPS set to shutdown the system in
> the event
> >> of power failure, then place both the UPS and asterisk
> servers in a
> >> locked rack. In the event of a power failure (or someone knocking
> >> the plug loose, which you can use locking plugs to further
> mitigate),
> >> the system will stay up on battery power then shut itself down to
> >> prevent data corruption. I doubt you will get that level
> of uptime,
> >> but there are other options to help achieve higher
> reliability. You
> >> can run the OS and asterisk on a solid state disk, and
> have voicemail
> >> and whatever else you want to go to rotating disks. That
> will also
> >> help with power usage on the server when using the UPS.
> Industrial
> >> flash disks are said to have (but they really can't
> promise this) a 3
> >> million hour MTBF.
> >>
> >> Thanks,
> >> Nick
> >>
> >> shadowym wrote:
> >>
> >>> The cold hard truth is that if Asterisk cannot achieve
> >>>
> >> 99.999% uptime
> >>
> >>> without becoming much more expensive that a traditional PBX
> >>>
> >> then it is
> >>
> >>> not a viable alternative. Even elcheapo Key systems are
> >>>
> >> rated for five nines.
> >>
> >>> That is what the telco world requires unless your just
> >>>
> >> using Asterisk
> >>
> >>> in your basement as a hobby or as a one man company.
> >>>
> >>> Redundant Servers is moving into the realm of
> non-competitive with
> >>> Traditional PBX IMHO.
> >>>
> >>> I don't care about corruption of the CDR or any of the
> >>> logging/database information. All I care about is the
> ability make
> >>> phone calls after power failure. That IS the MAIN function
> >>>
> >> of a PBX.
> >>
> >>> Not call centers, databases, CDR, click 2 call, and all the
> >>>
> >> other bells and whistles.
> >>
> >>>
> >>>
> >>>
> >>>
> >>>> -----Original Message-----
> >>>> From: Boris Bakchiev [mailto:boris at jildent.com.au]
> >>>> Sent: Tuesday, June 13, 2006 2:13 AM
> >>>> To: Asterisk Users Mailing List - Non-Commercial Discussion
> >>>> Subject: RE: [Asterisk-Users] Hard drive write cache
> >>>>
> >>>> These days you don't have to worry much about your write
> >>>>
> >> cache unless
> >>
> >>>> you're running application where once single byte changed
> >>>>
> >> will affect
> >>
> >>>> whole file.
> >>>>
> >>>> Look at it this way, the only corruption will occur is
> >>>>
> >> whatever the
> >>
> >>>> files were open by asterisk at the time of the crash. And
> >>>>
> >> only up to
> >>
> >>>> the point where the file was last open.
> >>>> As far as I know asterisk does not keep cdr or log files
> >>>>
> >> open so you
> >>
> >>>> would loose only the data that was written at the time of
> >>>>
> >> the power
> >>
> >>>> failure.
> >>>>
> >>>> Any journaling file system (ext3, resierfs, xfs, etc)
> will easily
> >>>> handle any power failure event. Your files will not be
> corrupt but
> >>>> could miss some of the data.
> >>>>
> >>>> At the most you will loose 10-50 cdr entries written to
> >>>>
> >> you log files.
> >>
> >>>> If you post CDR to a remote SQL database then you
> asterisk install
> >>>> and linux is more or less static and will not be affected by the
> >>>> power failure.
> >>>>
> >>>> What you need to do is minimise the writes to hard disk's:
> >>>>
> >>>> 1 - Send syslog to remote server and do not do ANY syslogs
> >>>> Or keep the circular buffer in memory if you have
> >>>>
> >> plenty of it.
> >>
> >>>> 2 - Send CDR's to SQL server (or log to ramdisk and send
> to remote
> >>>> server every few minutes via SSH)
> >>>> 3 - Do not record any calls (or do that somewhere else)
> >>>> 4 - Stop any services that write/read data on regular intervals.
> >>>>
> >>>> If you have no writes you have nothing to worry about
> during power
> >>>> failure and journaling file system will take care of the rest.
> >>>>
> >>>> Keep your partition size really small so that fsck will
> >>>>
> >> not take much
> >>
> >>>> time.
> >>>>
> >>>> You have to be realistic, you cannot achieve 99.999% uptime.
> >>>> That's 5 minutes per year downtime.
> >>>> You will have more or less 100% until your first
> hardware failure.
> >>>>
> >>>> Even if you have all the hardware components
> pre-purchased it will
> >>>> still take you 2-12 hours to detect, diagnose and fix
> the fault if
> >>>> you lucky.
> >>>> So your 5 minuets
> >>>>
> >>>> If the business is demanding 99.999% then it should be
> prepared to
> >>>> invest into the hardware.
> >>>> I would recommend a cluster or even better a fault
> tolerant server.
> >>>> Those are expensive but you can pretty much rule out the
> hardware
> >>>> failure and swap all of the failed components while the
> system is
> >>>> running (cpu, memory, hdd, etc).
> >>>>
> >>>> Look at Stratus or NEC FT servers if you need hardware
> redundancy.
> >>>> They're expensive but will give you the hardware
> >>>>
> >> reliability you need.
> >>
> >>>> Or get a traditional PABX :)
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: asterisk-users-bounces at lists.digium.com
> >>>>>
> >>>>>
> >>>> [mailto:asterisk-users-
> >>>>
> >>>>
> >>>>> bounces at lists.digium.com] On Behalf Of shadowym
> >>>>> Sent: Tuesday, 13 June 2006 10:34
> >>>>> To: asterisk-users at lists.digium.com
> >>>>> Subject: [Asterisk-Users] Hard drive write cache
> >>>>>
> >>>>>
> >>>>> I am looking at ways to harden my asterisk install to
> >>>>>
> >>>>>
> >>>> prevent computer
> >>>>
> >>>>
> >>>>> related issues from happening. I am concerned about about
> >>>>>
> >>>>>
> >>>> disk write
> >>>>
> >>>>
> >>>>> cache.
> >>>>> That seems to be a major source of hard drive
> corruption on power
> >>>>>
> >>>>>
> >>>> failure.
> >>>>
> >>>>
> >>>>> Hard Drive corruption is simply unacceptable for the
> >>>>>
> >> 99.999% uptime
> >>
> >>>>> requirements of my Asterisk install that needs to be as
> >>>>>
> >>>>>
> >>>> reliable as a
> >>>>
> >>>>
> >>>>> proprietary PBX.
> >>>>>
> >>>>> Of course I will be using redundant power supplies, raid
> >>>>>
> >> 1 and use a
> >>
> >>>>>
> >>>>>
> >>>> UPS.
> >>>>
> >>>>
> >>>>> None of those things mean much if the power cords
> accidentally get
> >>>>>
> >>>>>
> >>>> pulled
> >>>>
> >>>>
> >>>>> from the back of the server. Unlikely as it may be I have
> >>>>>
> >>>>>
> >>>> to consider
> >>>> ALL
> >>>>
> >>>>
> >>>>> possibilities.
> >>>>>
> >>>>> So is disabling the write cache a good way to reduce the
> >>>>>
> >>>>>
> >>>> risk of hard
> >>>>
> >>>>
> >>>>> drive corruption for an Asterisk server? I am not too
> >>>>>
> >>>>>
> >>>> concerned about
> >>>>
> >>>>
> >>>>> the reduced performance/lifetime of hardrives with write cache
> >>>>> disabled since
> >>>>>
> >>>>>
> >>>> Asterisk
> >>>>
> >>>>
> >>>>> is not a very write intensive environment. Even with lot's of
> >>>>>
> >>>>>
> >>>> voicemail
> >>>>
> >>>>
> >>>>> going on.
> >>>>>
> >>>>> Any other recommendations/links for increasing the
> reliability of
> >>>>>
> >>>>>
> >>>> Asterisk
> >>>>
> >>>>
>
>
More information about the asterisk-users
mailing list