tuning blockusage_bs and lessfs in general

[Morten Bohmer]

 Hi all

We have been using lessfs for a while as a secondary backup system. The performance has been variating, so we are now looking at tuning performance.

Our physical disk storage is at 1.2T and we have configured one lessfs volume with some files which are exposed to our hosts via iscsi as disks.

After changing blockusage_bs we get higher performance, for a while, then it takes a pause for 30-60 seconds and it will go at max speed again, we have tried to change commit_interval to 3,5,15,30 seconds, but it seems that delay is just more or less the same.


We have calculated the blockusage_bs parameter with the physical size of 1.2T and deduplicated size of 40T.... any suggestions on the calculations or why we experience this variating speed ?


our config:

DEBUG = 5
HASHNAME=MHASH_TIGER192
HASHLEN = 24
BLOCKDATA_IO_TYPE=file_io
BLOCKDATA_PATH=/mnt/vol1/lessfsArchive/data/blockdata.dta
META_PATH=/mnt/vol1/lessfsArchive/meta
META_BS=1048576
CACHESIZE=4096
COMMIT_INTERVAL=10
LISTEN_IP=127.0.0.1
LISTEN_PORT=100
MAX_THREADS=4
DYNAMIC_DEFRAGMENTATION=on
COREDUMPSIZE=2560000000
SYNC_RELAX=0
BACKGROUND_DELETE=on
ENCRYPT_DATA=on
ENCRYPT_META=off
ENABLE_TRANSACTIONS=on
BLKSIZE=131072
COMPRESSION=qlz
BLOCKUSAGE_BS=681574400
FREELIST_BS=681574400
TUNEFORSPEED=yes