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nova filesystem wikipedia jump to content main menu main menu move to sidebar hide navigation main page contents current events random article about wikipedia contact us contribute help learn to edit community portal recent changes upload file special pages search search appearance donate create account log in personal tools donate create account log in contents move to sidebar hide top 1 filesystem toggle filesystem subsection 1 1 log structure 1 2 copy on write 1 3 journaling 1 4 metadata protection 1 5 data protection 2 references 3 external links toggle the table of contents nova filesystem add languages add links article talk english read edit view history tools tools move to sidebar hide actions read edit view history general what links here related changes upload file permanent link page information cite this page get shortened url switch to legacy parser print export download as pdf printable version in other projects wikidata item appearance move to sidebar hide from wikipedia the free encyclopedia open source file system nova developers jian andiry xu lu zhang steven swanson university of california san diego computer science and engineering department preview release linux kernel 4 13 1 written in c operating system linux type file system driver license gpl repository github com nvsl linux nova the nova non volatile memory accelerated file system is an open source log structured file system for byte addressable persistent memory for example non volatile dual in line memory module nvdimm and 3d xpoint dimms for linux nova is designed specifically for byte addressable persistent memories and aims to provide high performance atomic file and metadata operations and fault tolerance to meet these goals nova combines several techniques found in other file systems nova uses log structure copy on write cow journaling and log structured metadata updates to provide strong atomicity guarantees and it uses a combination replication metadata checksums and raid 4 parity to protect data and metadata from media errors and software bugs it also supports checkpoints to facilitate backups filesystem edit nova was developed at the university of california san diego in the non volatile systems laboratory of the computer science and engineering department 2 3 patches were initially made available for version 4 12 of the linux kernel 4 as of 2017 update it is limited to x86 64 linux and not ready for merging with the upstream kernel 3 log structure edit this section needs more citations please help improve this section by adding citations to reliable sources unsourced material may be challenged and removed find sources nova filesystem news newspapers books scholar jstor september 2017 learn how and when to remove this message nova is primarily a log structured file system but it differs from other log structured file systems in several respects first rather than using a single log for the entire file system each inode has its own dedicated log that records the updates to the inode 3 this allows for increased concurrency in file operations since different threads can operate on inodes in parallel second the logs do not contain file data but only metadata updates resulting in smaller logs third the logs are not stored in physically contiguous memory instead nova stores the logs in a linked list of 4 kb memory pages nova uses the logs to provide atomicity for operations that affect a single file e g writing to a file or modifying its metadata to do this nova writes a log entry to empty space past the end of the log and then atomically updates the inode s pointer to the log tail copy on write edit nova uses copy on write cow to update file data when a program writes data to a file nova allocates some unused memory pages to hold the data and writes the data into them then it appends a log entry to the inode s log that points to the new pages and describes their logical location in the file since appending the log entry is atomic the write is also atomic journaling edit some file operations e g moving a file from one directory to another require modifying multiple inodes to make these operations atomic nova uses a simple journaling mechanism first it writes the new log entries to ends of the inodes that the operation will affect then it uses the journal to record the necessary updates to the inodes log tail pointers next it marks the journal as committed and applies the updates to the tail pointers metadata protection edit nova uses replication and checksums to provide protection against metadata corruption due to media errors and software bugs every metadata structure e g inodes superblocks and log entries contains a crc 32 checksum that allows nova to detect if structures contents have changed with its knowledge nova also stores two copies of each data structure the primary and the replica and stores them far from one another in memory whenever nova accesses a metadata structure it first recomputes the checksum on both the primary and the replica if either check results in a mismatch nova repairs the damage using the other copy if neither checksum matches then the structure is lost and nova returns an error data protection edit nova uses raid 4 to protect file data it divides each 4 kb page into 512 byte strips and stores a parity strip in a dedicated region of persistent memory it also computes and stores a replica of a crc 32 checksum for the eight data strips and the parity strip when nova reads a page it confirms the checksum on each strip if one of the strips is corrupt it tries to recover the strip using the parity bits if no other strips have experienced data corruption recovery will succeed otherwise recovery fails the contents of the page are lost and nova returns an error references edit linux nova retrieved 21 september 2017 via github nova the newest linux file system designed for persistent memory phoronix phoronix 1 2 3 the nova filesystem lwn net lwn net nova a new file system for persistent memory lwn net lwn net external links edit nova a log structured file system for hybrid volatile non volatile main memories hardening the nova file system ucsd cse techreport cs2017 1018 nova the fastest file system for nvdimms v t e file systems comparison of file systems distributed unix filesystem disk and non rotating adfs advfs amiga ffs amiga ofs apfs athfs bcachefs bfs be file system boot file system byte file system z vm btrfs cvfs dfs efs encrypting file system extent file system episode ext ext2 ext3 ext4 fat exfat files 11 fossil gpfs hammer hammer2 hfs classic mac os hfs mvs hfs hpfs htfs jfs lfs mfs macintosh file system tivo media file system minix netware file system next3 nilfs nilfs2 nss ntfs onefs openzfs pfs qfs qnx4fs refs reiserfs reiser4 reliance reliance nitro rfs sfs shared file system vm smart file system snfs soup apple tux3 ubifs ufs ufs2 soft updates wapbl vxfs wafl xiafs xfs xsan zfs z os zfs sun optical disc hsf iso 9660 iso 13490 udf flash memory and ssd apfs fat exfat tfat erofs f2fs nvfs host side wear leveling chfs jffs jffs2 logfs nilfs nilfs2 yaffs ubifs distributed parallel beegfs ceph gfs2 google file system ocfs2 orangefs pvfs qfs xsan more nas 9p afs openafs afp coda dfs google file system gpfs lustre ncp nfs pohmelfs hadoop smb cifs sshfs more specialized aufs axfs boot file system compact disc file system cramfs davfs2 erofs ftpfs fuse lnfs ltfs nova mvfs squashfs umsdos overlayfs unionfs pseudo configfs devfs debugfs kernfs procfs specfs sysfs tmpfs winfs encrypted ecryptfs encfs efs rubberhose sshfs zfs types clustered global grid self certifying flash journaling log structured object record oriented semantic steganographic synthetic versioning features case preservation copy on write data deduplication data scrubbing execute in place extent file attribute extended file attributes file change log fork inode links hard symbolic access control access control list filesystem level encryption permissions modes sticky bit interfaces file manager file system api installable file system virtual file system lists cryptographic default log structured layouts master boot record guid partition table apple partition map v t e linux kernel organization kernel linux foundation linux mark institute linus s law tanenbaum torvalds debate tux sco disputes linaro gnu gpl v2 menuconfig supported computer architectures version history criticism support developers the linux programming interface kernel org lkml linux conferences users linux user group lug people werner almesberger h peter anvin jens axboe moshe bar suparna bhattacharya andries brouwer rémy card alan cox matthew garrett avi kivity con kolivas greg kroah hartman robert love david s miller ingo molnár andrew morton hans reiser rusty russell shuah khan linus torvalds theodore ts o stephen tweedie harald welte chris wright technical debugging criu ftrace kdump linux kernel oops systemtap bpf ebpf startup vmlinux system map dracut initrd initramfs abis linux standard base x32 abi apis kernel system call interface posix ioctl select open read close sync linux only futex epoll splice dnotify inotify readahead in kernel alsa crypto api io_uring drm kernfs memory barrier new api rcu video4linux iio userspace daemons file systems bpffs configfs devfs devpts debugfs fuse hugetlbfs pipefs procfs securityfs sockfs sysfs tmpfs systemd udev kmscon binfmt_misc wrapper libraries c standard library glibc uclibc bionic libhybris dietlibc eglibc klibc musl newlib libcgroup libdrm libalsa libevdev libusb liburing components kernel modules bluez cgroups console bcache device mapper dm cache dm crypt drm edac evdev kernel same page merging ksm lio framebuffer lvm kms driver netfilter netlink nftables network scheduler perf slub zram zswap process and i o schedulers brain fuck scheduler completely fair scheduler cfs earliest eligible virtual deadline first eevdf noop scheduler o n scheduler o 1 scheduler sched_deadline sched_fifo sched_rr security modules apparmor exec shield seccomp selinux smack tomoyo linux linux pam device drivers 802 11 graphics raw device initramfs kernelcare kexec kgraft kpatch ksplice variants mainline linux kernel linux libre high performance computing ink compute node linux slurm real time computing rtlinux rtai xenomai preempt_rt mmu less μclinux psxlinux virtualization hypervisor kvm xen os level virtualization linux vserver lguest lxc openvz other l4linux user mode linux mklinux colinux adoption range of use desktop embedded gaming thin client ltsp server lamp lyme lyce devices adopters list of linux adopters linux portal free and open source software portal category v t e linux linux kernel history linus s law linux libre booting process kernel oops tux more controversies criticism of linux gnu linux naming controversy tanenbaum torvalds debate sco and linux distributions general comparison distributions list netbook specific comparison distributions that run from ram lightweight security focused operating system package manager package format list of software package managers organizations linuxchix linux counter linux documentation project linux foundation linux mark institute linux user group lug adoption adopters desktop embedded gaming mobile range of use state government sponsored linux malware media distrowatch free software magazine full circle linux com linux format linux gazette linux journal linux magazine linuxuser ubuntu user linux outlaws linux voice lugradio lwn net phoronix revolution os the code security certifications comptia linux linux foundation red hat linux portal free and open source software portal category retrieved from https en wikipedia org w index php title nova_ filesystem oldid 1344350696 categories free special purpose file systems free software programmed in c linux kernel features unix file system related software software using the gnu general public license hidden categories articles with short description short description is different from wikidata articles containing potentially dated statements from 2017 all articles containing potentially dated statements articles needing additional references from september 2017 all articles needing additional references this page was last edited on 19 march 2026 at 22 46 utc page was rendered with parsoid text is available under the creative commons attribution sharealike 4 0 license additional terms may apply by using this site you agree to the terms of use and privacy policy wikipedia is a registered trademark of the wikimedia foundation inc a non profit organization privacy policy about wikipedia disclaimers contact wikipedia legal safety contacts code of conduct developers statistics cookie statement mobile view search search toggle the table of contents nova filesystem add languages add topic