On 1/28/2012 9:34 AM, Peter Schuller wrote:
>> I'm using level compaction and I have about 200GB compressed in my
>> largest CFs. The disks are getting full. This is time-series data so I
>> want to drop data that is a couple of months old. It's pretty easy for
>> me to iterate through the relevant keys and delete the rows. But will
>> that do anything?
>> I currently have the majority of sstables at generation 4. Deleting rows
>> will initially just create a ton of tombstones. For them to actually
>> free up significant space they need to get promoted to gen 4 and cause a
>> compaction there, right? nodetool compact doesn't do anything with level
>> compaction, it seems. Am I doomed?
>> (Ok, I'll whip out my CC and order more disk ;-)
> There is a delay before you will see the effects of deletions in terms
> of disk space, yes. However, this is not normally a problem because
> you effectively reach a steady state of disk usage. It only becomes a
> problem if you're almost *entirely* full and are trying to delete data
> in a panic.
>
> How far away are you from entirely full? Are you just worried about
> the future or are you about to run out of disk space right now?
I'm at 80%, so not quite panic yet ;-)
I'm wondering, in the steady state, how much of the space used will
contain deleted data.
Thorsten
