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From Derek Andree <dand...@lacunasystems.com>
Subject Single node cassandra
Date Wed, 24 Aug 2011 01:52:23 GMT
I'm looking for advice for running cassandra 8.+ on a single node.   Would love to hear stories
about how much RAM you succeeded with, etc.

Currently we are running with a 4GB heap size.  Hardware is 4 cores and 8GB physical memory.
 We're not opposed to going to 16GB of memory or even 32GB.  We have fast 6GBps SAS drives,
although currently do not have a dedicated drive for Commit Log, but we are thinking about
trying this out.

Our application has time series data which means our data will get larger over time, not in
all CFs though.  We have 7 "hot" CFs but they are probably not that hot to someone running
a sizable cluster.  We have 15 CFs total in our keyspace.

I've already tweaked key cache and in some cases added a large enough row cache to keep an
entire CF in memory where appropriate.

Basically, I'm just curious under this sort of load if we can expect decent results with a
single node as the data gets larger.  I know this isn't necessarily a binary answer, just
curious about people's experiences on a single node.


Thanks,
-Derek


cfstats:


----------------
	Keyspace: test
	Read Count: 2869777
	Read Latency: 1.2266526890416922 ms.
	Write Count: 7672036
	Write Latency: 0.016663120975970395 ms.
	Pending Tasks: 0
		Column Family: DocData
		SSTable count: 1
		Space used (live): 425090
		Space used (total): 425090
		Number of Keys (estimate): 128
		Memtable Columns Count: 0
		Memtable Data Size: 0
		Memtable Switch Count: 0
		Read Count: 162
		Read Latency: NaN ms.
		Write Count: 0
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 27
		Key cache hit rate: NaN
		Row cache: disabled
		Compacted row minimum size: 771
		Compacted row maximum size: 315852
		Compacted row mean size: 18290

		Column Family: User
		SSTable count: 1
		Space used (live): 5368
		Space used (total): 5368
		Number of Keys (estimate): 128
		Memtable Columns Count: 0
		Memtable Data Size: 0
		Memtable Switch Count: 0
		Read Count: 0
		Read Latency: NaN ms.
		Write Count: 0
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache capacity: 1000
		Row cache size: 0
		Row cache hit rate: NaN
		Compacted row minimum size: 447
		Compacted row maximum size: 535
		Compacted row mean size: 535

		Column Family: SMapping
		SSTable count: 1
		Space used (live): 536900
		Space used (total): 536900
		Number of Keys (estimate): 768
		Memtable Columns Count: 9528
		Memtable Data Size: 4646940
		Memtable Switch Count: 0
		Read Count: 763
		Read Latency: NaN ms.
		Write Count: 763
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 763
		Key cache hit rate: NaN
		Row cache capacity: 1000
		Row cache size: 763
		Row cache hit rate: NaN
		Compacted row minimum size: 447
		Compacted row maximum size: 73457
		Compacted row mean size: 713

		Column Family: LObject
		SSTable count: 2
		Space used (live): 6945430
		Space used (total): 6945430
		Number of Keys (estimate): 10752
		Memtable Columns Count: 729638
		Memtable Data Size: 400799230
		Memtable Switch Count: 2
		Read Count: 316756
		Read Latency: NaN ms.
		Write Count: 147028
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 20000
		Key cache size: 20000
		Key cache hit rate: NaN
		Row cache capacity: 20000
		Row cache size: 5304
		Row cache hit rate: NaN
		Compacted row minimum size: 259
		Compacted row maximum size: 182785
		Compacted row mean size: 661

		Column Family: SMeta
		SSTable count: 2
		Space used (live): 173059487
		Space used (total): 343520951
		Number of Keys (estimate): 165760
		Memtable Columns Count: 442764
		Memtable Data Size: 168300272
		Memtable Switch Count: 53
		Read Count: 2345765
		Read Latency: 0.009 ms.
		Write Count: 2179885
		Write Latency: 0.033 ms.
		Pending Tasks: 0
		Key cache: disabled
		Row cache capacity: 100000
		Row cache size: 82940
		Row cache hit rate: 1.0
		Compacted row minimum size: 925
		Compacted row maximum size: 1109
		Compacted row mean size: 1109

		Column Family: SLookback
		SSTable count: 14
		Space used (live): 16604796474
		Space used (total): 17754314562
		Number of Keys (estimate): 2515968
		Memtable Columns Count: 49500
		Memtable Data Size: 38927091
		Memtable Switch Count: 18
		Read Count: 194587
		Read Latency: 13.929 ms.
		Write Count: 200732
		Write Latency: 0.011 ms.
		Pending Tasks: 0
		Key cache capacity: 200000
		Key cache size: 200000
		Key cache hit rate: 0.2599537318884695
		Row cache: disabled
		Compacted row minimum size: 311
		Compacted row maximum size: 35425
		Compacted row mean size: 7338

		Column Family: Event
		SSTable count: 2
		Space used (live): 23480776
		Space used (total): 23480776
		Number of Keys (estimate): 33280
		Memtable Columns Count: 77
		Memtable Data Size: 5310
		Memtable Switch Count: 1
		Read Count: 12
		Read Latency: NaN ms.
		Write Count: 12
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 10000
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache capacity: 1000
		Row cache size: 0
		Row cache hit rate: NaN
		Compacted row minimum size: 643
		Compacted row maximum size: 770
		Compacted row mean size: 770

		Column Family: SHourly
		SSTable count: 3
		Space used (live): 847441284
		Space used (total): 847441284
		Number of Keys (estimate): 496768
		Memtable Columns Count: 35256
		Memtable Data Size: 67814381
		Memtable Switch Count: 3
		Read Count: 0
		Read Latency: NaN ms.
		Write Count: 330520
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache: disabled
		Compacted row minimum size: 180
		Compacted row maximum size: 9887
		Compacted row mean size: 1835

		Column Family: ConfigSettings
		SSTable count: 1
		Space used (live): 4854
		Space used (total): 4854
		Number of Keys (estimate): 128
		Memtable Columns Count: 0
		Memtable Data Size: 0
		Memtable Switch Count: 0
		Read Count: 135
		Read Latency: 0.007 ms.
		Write Count: 0
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 100
		Key cache size: 1
		Key cache hit rate: NaN
		Row cache capacity: 100
		Row cache size: 1
		Row cache hit rate: 1.0
		Compacted row minimum size: 536
		Compacted row maximum size: 642
		Compacted row mean size: 642

		Column Family: SystemMeta
		SSTable count: 2
		Space used (live): 9258
		Space used (total): 9258
		Number of Keys (estimate): 256
		Memtable Columns Count: 48
		Memtable Data Size: 2570
		Memtable Switch Count: 1
		Read Count: 18
		Read Latency: NaN ms.
		Write Count: 10
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 100
		Key cache size: 1
		Key cache hit rate: NaN
		Row cache capacity: 100
		Row cache size: 1
		Row cache hit rate: NaN
		Compacted row minimum size: 311
		Compacted row maximum size: 372
		Compacted row mean size: 372

		Column Family: LConfig
		SSTable count: 2
		Space used (live): 22198
		Space used (total): 22198
		Number of Keys (estimate): 256
		Memtable Columns Count: 3614
		Memtable Data Size: 399019
		Memtable Switch Count: 1
		Read Count: 261
		Read Latency: NaN ms.
		Write Count: 261
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 9
		Key cache hit rate: 0.0
		Row cache capacity: 1000
		Row cache size: 9
		Row cache hit rate: NaN
		Compacted row minimum size: 643
		Compacted row maximum size: 770
		Compacted row mean size: 770

		Column Family: S
		SSTable count: 6
		Space used (live): 4845200284
		Space used (total): 4926197540
		Number of Keys (estimate): 496512
		Memtable Columns Count: 61093
		Memtable Data Size: 116164716
		Memtable Switch Count: 26
		Read Count: 11318
		Read Latency: 76.083 ms.
		Write Count: 2215986
		Write Latency: 0.008 ms.
		Pending Tasks: 0
		Key cache capacity: 5000
		Key cache size: 5000
		Key cache hit rate: 0.0018995517057974318
		Row cache: disabled
		Compacted row minimum size: 216
		Compacted row maximum size: 105778
		Compacted row mean size: 10079

		Column Family: SLookbackLog
		SSTable count: 2
		Space used (live): 23988670
		Space used (total): 23988670
		Number of Keys (estimate): 10496
		Memtable Columns Count: 111401
		Memtable Data Size: 50531214
		Memtable Switch Count: 7
		Read Count: 0
		Read Latency: NaN ms.
		Write Count: 2431579
		Write Latency: 0.007 ms.
		Pending Tasks: 0
		Key cache capacity: 10496
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache capacity: 10496
		Row cache size: 0
		Row cache hit rate: NaN
		Compacted row minimum size: 73
		Compacted row maximum size: 20501
		Compacted row mean size: 2484

		Column Family: Tag
		SSTable count: 0
		Space used (live): 0
		Space used (total): 0
		Number of Keys (estimate): 0
		Memtable Columns Count: 0
		Memtable Data Size: 0
		Memtable Switch Count: 0
		Read Count: 0
		Read Latency: NaN ms.
		Write Count: 0
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache capacity: 1000
		Row cache size: 0
		Row cache hit rate: NaN
		Compacted row minimum size: 0
		Compacted row maximum size: 0
		Compacted row mean size: 0

		Column Family: SDaily
		SSTable count: 1
		Space used (live): 60375798
		Space used (total): 60375798
		Number of Keys (estimate): 166016
		Memtable Columns Count: 165260
		Memtable Data Size: 8056425
		Memtable Switch Count: 0
		Read Count: 0
		Read Latency: NaN ms.
		Write Count: 165260
		Write Latency: NaN ms.
		Pending Tasks: 0
		Key cache capacity: 1000
		Key cache size: 0
		Key cache hit rate: NaN
		Row cache: disabled
		Compacted row minimum size: 150
		Compacted row maximum size: 446
		Compacted row mean size: 284

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