>Lincoln Yeoh wrote:
>>
>> >Lincoln Yeoh wrote:
>> >For example: you could then stick the WAL on a battery backed up RAM disk.
>> >How much total space does a WAL log need?
>> >
>> >A battery backed RAM disk might even be cheaper than Brand X RDBMS
>> >Proprietary Feature #5.
>>
>> And your experiments do help show that it is useful to be able to specify
>> where things go, that putting just the WAL somewhere else makes things 20%
>> faster. So you don't have to put everything on a pgfs. Just the WAL on some
>> other FS (even FAT32, ick ;) ).
At 02:04 PM 5/6/01 +0200, Hannu Krosing wrote:
>So you propose pgwalfs ? ;)
Nah. I'm proposing the opposite in fact.
I'm saying so far there appears to be no real need to come up with a
special filesystem. Stick to using existing/future filesystems. Just make
it easy and safe enough for DBA's to put the objects on whatever filesystem
they choose. So long as the O/S kernel/driver people support the hardware
or filesystem, postgresql will take advantage of it with little if any
extra work.
In fact as mlw's experiments show, you can put the WAL on FAT (FAT16?) for
a 20% performance increase. How much better would a raw device be? Would it
really be worth all that hassle? For instance if you need to resize the FAT
partition, you could probably use fips, Partition Magic or some other cost
effective solution - no need for pgsql developers or anybody to reinvent
anything.
My proposed but untested idea is that you could get a significant
performance increase by putting the WAL on popular filesystems running on
battery backed RAM drives (or other special hardware). 128MB RAM should be
enough for small setups?
Don't know how much these things cost, but I believe that when you need the
speed, they'll be more worthwhile than a special proprietary filesystem.
Ok, just found:
http://www.expressdata.com.au/Products/ProductsList.asp?SUPPLIER_NAME=PLATYP
US+TECHNOLOGY&SUBCATEGORY_NAME=QikDrive2#PRODUCTTITLE
AUD$1,624.70 = USD843.06. Not cheap but not way out of reach. Haven't found
other competing products yet. Must be somewhere.
Cheerio,
Link.
