Обсуждение: PostgreSQL on a CompactFlash

Am Donnerstag, 31. Januar 2008 schrieb Andre Nieder:
> So is there any reason that should prevent us from using PostgreSQL in
> combination with a compact flash?

I suggest you review the previous discussions on this topic.  Search
for "compact flash" on archives.postgresql.org.  You will find that
PostgreSQL very write-happy and you might have some work to do.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

  Hi Andre,
>
> As you know a cf card has not an unlimited amount of accesses…
>
Do we really know?
Or are we just repeating the same story we were told once?
I know that technically speaking you are right but the media have smart
contollers to avoid problems with this fact.
I remember reading in a german computer journal that they were trying
really hard to write a USB stick to death but gave up after 16 000 000
write cycles to the same logical adress without any error.

Is there a theoretical limit or a practical one?
I'd be really interested in a real world test - does postgres work on as
cf-card/usb-stick and how long?
If anyone has got numbers - please let me know.

Regards,

Brar

Am 2008-01-31 12:03:00, schrieb Andre Nieder:
> Hello,
>
>
>
> we like to use PostgreSQL in an embedded system that runs - don't laugh
> - on a compact flash.

I have this too...

> Therefore we need to know how often PostgreSQL will write to the disc.

PostgreSQL in a normal installation of, e.g. a 8 GByte HighSpeed CF-Card
will kill your card in less then one month mayb arround two weeks.

> Once our system is configured there are very little changes to the
> database.

Like here...

> We have some tables in memory and some stored on the cf.
>
> If we change a table in memory, will PosgreSQL access the cf?

Configure the PostgreSQL as needed and then create a RAM-Disk for the
data/ directory.  shutdown the PostgreSQL and tar the whole RAM-Disk
and before you start uncompress it...

> As you know a cf card has not an unlimited amount of accesses...

:-)

> So is there any reason that should prevent us from using PostgreSQL in
> combination with a compact flash?

Maybe the limit of the Memory of your system.

I am using a 3Ware 3W85xx-8 with three 1 GByte Cards (Raid-1 + Hotfix),
one singel 1 GByte Card (/var/log) and four 8 GByte Cards (Raid-5 +
Hotfix) for the Data (the Postgresql.tar.gz and static data)

The TAR Archive is around 5 GByte (PostgreSQL has already compressed the
Stuff) and I was forced to install 12 GByte of Memory.

Thanks, Greetings and nice Day
    Michelle Konzack
    Systemadministrator
    Tamay Dogan Network
    Debian GNU/Linux Consultant


--
Linux-User #280138 with the Linux Counter, http://counter.li.org/
##################### Debian GNU/Linux Consultant #####################
Michelle Konzack   Apt. 917                  ICQ #328449886
                   50, rue de Soultz         MSN LinuxMichi
0033/6/61925193    67100 Strasbourg/France   IRC #Debian (irc.icq.com)