Hi I''m thinking about to change from Linux/Softwareraid to OpenSolaris/ZFS. During this, I''ve got some (probably stupid) questions: 1. Is ZFS able to encrypt all the data? If yes: How safe is this encryption? I''m currently using dm-crypt on linux for doing this. 2. How big is the usable diskspace? I know that a rai5 is using the space of one disk for parity informations. A raid5 with four disk of 300GB has 900GB Space. How is it with ZFS? How much space do I have in this case? thanks, Thomas
Hi, Thomas Deutsch wrote:> Hi > > I''m thinking about to change from Linux/Softwareraid to > OpenSolaris/ZFS. During this, I''ve got some (probably stupid) > questions:don''t worry, there are no stupid questions :).> 1. Is ZFS able to encrypt all the data? If yes: How safe is this > encryption? I''m currently using dm-crypt on linux for doing this.Encryption for ZFS is a planned feature, but not available now. See: http://www.opensolaris.org/os/project/zfs-crypto/ Another project is an encrypted loopback device called xlofi which can be used on top of ZFS: http://www.opensolaris.org/os/community/security/projects/xlofi/ I understand that both approaches are independent of the encryption mechanism, so one would be free to choose a suitably safe cypher that is supported by the Solaris Cryptographic Framework.> 2. How big is the usable diskspace? I know that a rai5 is using the > space of one disk for parity informations. A raid5 with four disk of > 300GB has 900GB Space. How is it with ZFS? How much space do I have in > this case?ZFS'' RAIDZ1 uses one parity disk per RAIDZ set, similarly to RAID-5. ZFS'' RAIDZ2 uses two parity disks per RAIDZ set. So, the amount of usable space can be computed by number of disks per RAIDZ set minus 1 or 2 depending on the algorithm times the minimum capacity per disk. Same calculation as with traditional RAID. But there are advantages for RAIDZ over traditional RAID-5: - No RAID-5 write hole. - Better performance through serialization of write requests. - Better performance through eliminating the need for read-modify-write. - Better data integrity through end-to-end checksums. - Faster re-syncing of replaced disks since you only need to recreate used blocks. - Compression can be easily switched on for some extra space depending of the nature of the data. See also: http://blogs.sun.com/roller/page/bonwick?entry=raid_z Best regards, Constantin -- Constantin Gonzalez Sun Microsystems GmbH, Germany Platform Technology Group, Client Solutions http://www.sun.de/ Tel.: +49 89/4 60 08-25 91 http://blogs.sun.com/constantin/
Hi 2006/8/22, Constantin Gonzalez <Constantin.Gonzalez at sun.com>:> Thomas Deutsch wrote: > > I''m thinking about to change from Linux/Softwareraid to > > OpenSolaris/ZFS. During this, I''ve got some (probably stupid) > > questions: > > don''t worry, there are no stupid questions :). > > > 1. Is ZFS able to encrypt all the data? If yes: How safe is this > > encryption? I''m currently using dm-crypt on linux for doing this. > > Encryption for ZFS is a planned feature, but not available now. See: > > http://www.opensolaris.org/os/project/zfs-crypto/ > > Another project is an encrypted loopback device called xlofi which can > be used on top of ZFS: > > http://www.opensolaris.org/os/community/security/projects/xlofi/ > > I understand that both approaches are independent of the encryption > mechanism, so one would be free to choose a suitably safe cypher that > is supported by the Solaris Cryptographic Framework.Thanks for this informaton. I''m waiting for encryption until I would use ZFS.> > 2. How big is the usable diskspace? I know that a rai5 is using the > > space of one disk for parity informations. A raid5 with four disk of > > 300GB has 900GB Space. How is it with ZFS? How much space do I have in > > this case? > > ZFS'' RAIDZ1 uses one parity disk per RAIDZ set, similarly to RAID-5. > ZFS'' RAIDZ2 uses two parity disks per RAIDZ set.This means that RAIDZ2 allows problems with two disks? thanks, Thomas
On Tue, Aug 22, 2006 at 07:02:53PM +0200, Thomas Deutsch wrote:> >ZFS'' RAIDZ1 uses one parity disk per RAIDZ set, similarly to RAID-5. > >ZFS'' RAIDZ2 uses two parity disks per RAIDZ set. > > This means that RAIDZ2 allows problems with two disks?That''s right. A third failure would cause data loss, but two failures are fine. --Bill