Flashcache
Allikas: Kuutõrvaja
Flashcache
Flashcashe on tehnoloogia selleks, et cacheda kirjutamisi-lugemisi kasutades kiiret SSD ketast vahelaona.
# apt-get install gcc make git-core dkms build-essential linux-headers-`uname -r` -y # git clone https://github.com/facebook/flashcache.git # cd flashcache # make # make install
Meil on serveris kaks ketast
- /dev/rbd1 (cehphis loodud võrguketas)
- /dev/sdb (lokaalne ssd)
Laadime mooduli
# modprobe flashcache
Dmesg peaks raporteerima
[1023454.971735] flashcache: flashcache-3.1.1 initialized
Järgmisena on vaja flascache_create töövahendiga kombineerida kaks blokkseadet device mapperis. Pole vaja karta, midagi olemasoleva rbd ketta ja sela oleva infoga ei juhtu
Haagime rbd ketta lahti
# umount /home
Süntaks on käsul järgnev
- flashcache_create home_cached <võtmed> <tekitatav ketas> <ssd> <aeglane ketas>
# flashcache_create -p back -s 230G -b 4k backup_cached /dev/sdb /dev/rbd0 cachedev backup_cached, ssd_devname /dev/sdb, disk_devname /dev/rbd0 cache mode WRITE_BACK block_size 8, md_block_size 8, cache_size 482344960 Flashcache metadata will use 1265MB of your 24154MB main memory
Võtmete selgitused
- -p: operate in writeback mode, which means that we cache both write and read requests
- -s: set the size of the cache, it should be the same as the size of your partition
- -b: set the block size to 4K
- backup_cached: flashcache seadme nimetus
haagime tekkinud seadme külge
# mount /dev/mapper/backup_cached /mnt/
Vaatame tulemust
# df -h Filesystem Size Used Avail Use% Mounted on ... /dev/mapper/backup_cached 32T 65G 32T 1% /mnt
Statistika vaatmiseks
# dmsetup table backup_cached: 0 68719460352 flashcache conf: ssd dev (/dev/sdb), disk dev (/dev/rbd0p1) cache mode(WRITE_BACK) capacity(237542M), associativity(512), data block size(4K) metadata block size(4096b) disk assoc(0K) skip sequential thresh(0K) total blocks(60810752), cached blocks(60160782), cache percent(98) dirty blocks(46144348), dirty percent(75) nr_queued(0) Size Hist: 1024:5 4096:217130775
Selleks, et boodil võetaks süsteem külge tuleb flashcache kaustas käivitada käsk
# make -f Makefile.dkms boot_conf
Seadme laadimiseks
# flashcache_load /dev/sdb1 backup_cached
Seadme hävitamiseks
# flashcache_destroy /dev/sdb1