ZFS A replacement for LVMs


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ZFS – A replacement for Traditional LVMs?: 

ZFS – A replacement for Traditional LVMs? Dwai Lahiri

Understanding ZFS: 

Understanding ZFS What is ZFS? Inner-workings of ZFS How is it different from other Software LVMs such as VxVM?

The inner-workings of ZFS: 

The inner-workings of ZFS

Vdev Label == Private Region: 

Vdev Label == Private Region

Details of the Vdev Label: 

Details of the Vdev Label

Features of ZFS: 

Features of ZFS List features of ZFS with brief explanation ZFS presents a pooled storage model that completely eliminates the concept of volumes and the associated problems of partitions, provisioning, wasted bandwidth and stranded storage. Thousands of file systems can draw from a common storage pool, each one consuming only as much space as it actually needs. The combined I/O bandwidth of all devices in the pool is available to all filesystems at all times. All operations are copy-on-write transactions, so the on-disk state is always valid RAID-Z – introduced to prevent RAID-5 write-hole by employing full-stripe writes (as opposed to variable width writes) Disk Scrubbing – similar to ECC memory scrubbing. the idea is to read all data to detect latent errors while they're still correctable. A scrub traverses the entire storage pool to read every copy of every block, validate it against its 256-bit checksum, and repair it if necessary. All this happens while the storage pool is live and in use. ZFS has a pipelined I/O engine, similar in concept to CPU pipelines. The pipeline operates on I/O dependency graphs and provides scoreboarding, priority, deadline scheduling, out-of-order issue and I/O aggregation. Snap-shots and Clones Built-in compression

Applications of ZFS: 

Applications of ZFS Where is ZFS best applicable? Based on the internals of ZFS, it seems best fit for File shares, NFS repositories, web platforms, container-based virtualization etc. Can it fit in an enterprise Datacenter? Yes According to Sun, ZFS fits into a wide-gamut of applicability – DBs, NFS shares, Virtualization solutions, Web application stores Clustering applicability Active/Active (parallel mode) – Not at present Active/Passive (failover mode) – Possible and supported in Sun Cluster 3.2 Active/Passive mode works in VCS but no Agent has been provided by Symantec yet (there is a custom Agent available through user-community efforts) Replication (aka VVR)? – Not at present

ZFS Portability (failing over between systems): 

ZFS Portability (failing over between systems) Failover/Failback of ZFS pools # zfs export <pool> exports (or in VxVM parlance “deports”) the zfs pool # zfs import scans the storage subsystem of the server for potential pools to import (akin to vxdisk –o alldgs list) # zfs import <pool> imports (similar to VxVM dg import) into the system Zfs doesn’t care about “endian-ness” of the target host (so you can move data pools across different hardware architectures (move pools from sparc to x86/x64 and vice versa) The Disks/LUNs have to be presented to each node of a multi-node “cluster”.

Performance vs Usability: 

Performance vs Usability Performance vs Usability Does zfs perform better than VxFS? According to published benchmarks, zfs has indeed outperformed VxFS (ref: http://www.sun.com/software/whitepapers/solaris10/zfs_veritas.pdf) How “Usable” is zfs, really? Only in-house proof-of-concept on for various applications will give us the ability to assess this. According to Sun, ZFS is fully usable in a production environment. Some key areas to “try” ZFS out in – Oracle Databases Oracle RAC Web-based Applications NFS shares CIFS-shares (Windows File server-type applicability) Virtualization (Solaris 10 Zones w/ ZFS filesystems/volumes)

How is it different from Traditional LVMs such as VxVM/VxFS?: 

How is it different from Traditional LVMs such as VxVM/VxFS?

How is it different from Traditional LVMs such as VxVM/VxFS?: 

How is it different from Traditional LVMs such as VxVM/VxFS?


Reference http://www.sun.com/software/whitepapers/solaris10/zfs_veritas.pdf http://www.opensolaris.org/os/community/zfs/docs/ondiskformat0822.pdf http://docs.huihoo.com/opensolaris/solaris-zfs-administration-guide/html/ch04s06.html http://www.opensolaris.org/os/community/zfs/whatis/ http://www.opensolaris.org/os/community/zfs/docs/zfs_last.pdf http://blogs.sun.com/ontherecord/entry/now_available_three_new_solaris