How many tablets can bigtable store?

[Roger <ro...@qq.com>]

Hi everyone,
I was reading bigtable paper these days.
And from the paper, I have a little question.


"Each METADATA row stores approximately 1KB of data in memory. With a modest limit of 128 MB 
METADATA tablets, our three-level location scheme is sufficient to address 2^34 tablets."


I am confusing because 2^10 * 2^7 = 2^17
How could it store 2^34 tablets?


------------------
Regards, 
Q

Re: How many tablets can bigtable store?

[lars hofhansl <lh...@yahoo.com>]

Hi Roger,

I think the math goes like this:
If the root tablet is held in 128mb memory and each entry is 1k that means that there can be 128mb/1k = 131072 = 2^17 meta tablets.
By the same logic each meta tablet can hold 2^17 entries, so you get 2^17 * 2^17 = 2^34 tablets in total.

-- Lars



________________________________
 From: Roger <ro...@qq.com>
To: user <us...@hbase.apache.org> 
Sent: Saturday, February 4, 2012 5:20 AM
Subject: How many tablets can bigtable store?
 
Hi everyone,
I was reading bigtable paper these days.
And from the paper, I have a little question.


"Each METADATA row stores approximately 1KB of data in memory. With a modest limit of 128 MB 
METADATA tablets, our three-level location scheme is sufficient to address 2^34 tablets."


I am confusing because 2^10 * 2^7 = 2^17
How could it store 2^34 tablets?


------------------
Regards, 
Q