This is because of the "warm up" of Cassandra as it starts. On a start it will start fetching the rows that were cached: this will have to be loaded from the disk, as there is nothing in the cache yet. You can read more about this at http://wiki.apache.org/cassandra/LargeDataSetConsiderations
2012/2/13 Franc Carter <franc.car...@sirca.org.au> > On Mon, Feb 13, 2012 at 5:03 PM, zhangcheng <zhangch...@jike.com> wrote: > >> ** >> >> I think the keycaches and rowcahches are bothe persisted to disk when >> shutdown, and restored from disk when restart, then improve the performance. >> > > Thanks - that would explain at least some of what I am seeing > > cheers > > >> >> 2012-02-13 >> ------------------------------ >> zhangcheng >> ------------------------------ >> *发件人：* Franc Carter >> *发送时间：* 2012-02-13 13:53:56 >> *收件人：* user >> *抄送：* >> *主题：* keycache persisted to disk ? >> >> Hi, >> >> I am testing Cassandra on Amazon and finding performance can vary fairly >> wildly. I'm leaning towards it being an artifact of the AWS I/O system but >> have one other possibility. >> >> Are keycaches persisted to disk and restored on a clean shutdown and >> restart ? >> >> cheers >> >> -- >> >> *Franc Carter* | Systems architect | Sirca Ltd >> <marc.zianideferra...@sirca.org.au> >> >> franc.car...@sirca.org.au | www.sirca.org.au >> >> Tel: +61 2 9236 9118 >> >> Level 9, 80 Clarence St, Sydney NSW 2000 >> >> PO Box H58, Australia Square, Sydney NSW 1215 >> >> > > > -- > > *Franc Carter* | Systems architect | Sirca Ltd > <marc.zianideferra...@sirca.org.au> > > franc.car...@sirca.org.au | www.sirca.org.au > > Tel: +61 2 9236 9118 > > Level 9, 80 Clarence St, Sydney NSW 2000 > > PO Box H58, Australia Square, Sydney NSW 1215 > >
