Durability of in-memory column family

["Liu, Ming (HPIT-GADSC)" <mi...@hp.com>]

Hi, all,

I want to use a column family to save some runtime data, which is small so I set that CF in memory to increase the performance, and the user data is still save in a normal CF.
My question is: will the data in the in-memory column family get lost, if there is a failure of regionServer?  Or in other words, is the data in an in-memory CF as safe as in an ordinary CF? No difference?

I could do test myself, but it needs some time, so I would like to be lazy and ask for help here :) If someone happened to know the answer, thanks in advance!

Thanks,
Ming

Re: Durability of in-memory column family

[Jean-Marc Spaggiari <je...@spaggiari.org>]

Hi Ming,

In memory means that HBase will try to keep the data in memory as much as
possible for fast response time, but at no time HBase will put your data at
risk. You data will still go first in the WAL and be persisted into disk.

The in memory option is to tell HBase to try to keep this data in the
memory cache (Block cache) as much as possible.

HTH.

JM

2015-01-05 21:28 GMT-05:00 Liu, Ming (HPIT-GADSC) <mi...@hp.com>:

> Hi, all,
>
> I want to use a column family to save some runtime data, which is small so
> I set that CF in memory to increase the performance, and the user data is
> still save in a normal CF.
> My question is: will the data in the in-memory column family get lost, if
> there is a failure of regionServer?  Or in other words, is the data in an
> in-memory CF as safe as in an ordinary CF? No difference?
>
> I could do test myself, but it needs some time, so I would like to be lazy
> and ask for help here :) If someone happened to know the answer, thanks in
> advance!
>
> Thanks,
> Ming
>