lz4 is supposed to achieve similar compression while using less resources then snappy. It is easy to test, just change then run a 'nodetool rebuild' . Not sure when lz4 was introduced but being that it is new to cassandra there may not be many large deployments running it yet.
On Thu, May 16, 2013 at 4:40 PM, Keith Wright <kwri...@nanigans.com> wrote: > Thank you for that. I did not have trickle_fsync enabled and will give it > a try. I just noticed that when running a describe on my table, I do not > see the sstable size parameter (compaction_strategy_options = > {'sstable_size_in_mb':5}) included. Is that expected? Does it mean its > using the defaults? > > Assuming none of the tuning here makes a noticeable difference, my next > step is to try switching from LZ4 to Snappy. Any opinions on that? > > Thanks! > > CREATE TABLE global_user ( > user_id bigint, > app_id int, > type text, > name text, > extra_param map<text, text>, > last timestamp, > paid boolean, > sku_time map<text, timestamp>, > values map<timestamp, float>, > PRIMARY KEY (user_id, app_id, type, name) > ) WITH > bloom_filter_fp_chance=0.100000 AND > caching='KEYS_ONLY' AND > comment='' AND > dclocal_read_repair_chance=0.000000 AND > gc_grace_seconds=86400 AND > read_repair_chance=0.100000 AND > replicate_on_write='true' AND > populate_io_cache_on_flush='false' AND > compaction={'class': 'LeveledCompactionStrategy'} AND > compression={'chunk_length_kb': '8', 'crc_check_chance': '0.1', > 'sstable_compression': 'LZ4Compressor'}; > > From: Igor <i...@4friends.od.ua> > Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org> > Date: Thursday, May 16, 2013 4:27 PM > To: "user@cassandra.apache.org" <user@cassandra.apache.org> > Subject: Re: SSTable size versus read performance > > just in case it will be useful to somebody - here is my checklist for > better read performance from SSD > > 1. limit read-ahead to 16 or 32 > 2. enable 'trickle_fsync' (available starting from cassandra 1.1.x) > 3. use 'deadline' io-scheduler (much more important for rotational drives > then for SSD) > 4. format data partition starting on 2048 sector boundary > 5. use ext4 with noatime,nodiratime,discard mount options > > On 05/16/2013 10:48 PM, Edward Capriolo wrote: > > I was going to say something similar I feel like the SSD drives read much > "more" then the standard drive. Read Ahead/arge sectors could and probably > does explain it. > > > On Thu, May 16, 2013 at 3:43 PM, Bryan Talbot <btal...@aeriagames.com>wrote: > >> 512 sectors for read-ahead. Are your new fancy SSD drives using large >> sectors? If your read-ahead is really reading 512 x 4KB per random IO, >> then that 2 MB per read seems like a lot of extra overhead. >> >> -Bryan >> >> >> >> >> On Thu, May 16, 2013 at 12:35 PM, Keith Wright <kwri...@nanigans.com>wrote: >> >>> We actually have it set to 512. I have tried decreasing my SSTable size >>> to 5 MB and changing the chunk size to 8 kb >>> >>> From: Igor <i...@4friends.od.ua> >>> Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org> >>> Date: Thursday, May 16, 2013 1:55 PM >>> >>> To: "user@cassandra.apache.org" <user@cassandra.apache.org> >>> Subject: Re: SSTable size versus read performance >>> >>> My 5 cents: I'd check blockdev --getra for data drives - too high values >>> for readahead (default to 256 for debian) can hurt read performance. >>> >>> > >