Actually, ZFS takes the concept of a journaled filesystem further. In effect, it is a database used as a general purpose data store. Leaving the underlying volume-management functionality (similar to much of what is in VxVM 5, leaving aside the question of the algorithm for RAID), the filesystem is different in that it uses copy-on-write and transactions. Just as MySQL or Oracle et al do, a transaction isn't committed until it is complete. Any incomplete transactions are rolled back. The result is that you never need (nor is the operation supported) an fsck on a ZFS filesystem. A pool can become inconsistent at the device level requiring a scrub (perhaps a device lost connectivity or outright failed and was replaced) but this is a volume management function and is no different in principle (details are of course different) from VxVM recover on a RAID 1/5/10 volume.
BTW yes you can use ZFS on a VxVM volume. That is, you can add VxVM volumes as devices in a zpool. This is not recommended but it works. It can be useful in migrating part of your data off of Vx -- e.g. older Filenet (< 4.12) require use of VxVM volumes for the database. If you wanted, esp. in preparing an upgrade path to 4.12 which supports ZFS zvol, to move things around the network by using ZFS snapshots with zfs send and zfs receive but your origination system has all storage under VxVM control then you might well create a zpool from some VxVM volumes and put ZFS filesystems on there for use by Oracle and for holding binaries etc. all with local file copy. Then you move to your new host built with ZFS by doing a ZFS snapshot send receive sequence. While VxFS supports snapshots, I'm not aware of a mechanism to transmit that across a network to another host where it gets auto-reconstructed. I'm not real sure that there's anything to gain in a SAN environment by using VxVM for the sake of the ASL but putting ZFS on top for production use. I am open to suggestions and examples for this case. > -----Original Message----- > From: veritas-vx-boun...@mailman.eng.auburn.edu > [mailto:veritas-vx-boun...@mailman.eng.auburn.edu] On Behalf > Of Thomas Graham > Sent: Wednesday, March 03, 2010 12:25 AM > To: William Havey > Cc: veritas-vx@mailman.eng.auburn.edu > Subject: Re: [Veritas-vx] inode invalid?! > > I see, so checking lost and found dir is an important step > > On Tuesday, March 2, 2010, William Havey <bbha...@gmail.com> wrote: > > The purpose of fsck is to make a file system mountable. If > this requires putting some unaccounted for file system block > into the lost+found directory, leaving the admin to decide > what to do with the block, so be it. A file system simply can > not guarantee data integrity under every conceivable > circumstance. That's why redundancy is built into either the > hardware, if the situations cause is hardware failure, the > array provides a good copy, or the storage software, through > mirroring. > > > > > > On Tue, Mar 2, 2010 at 7:18 AM, Thomas Graham > <lktho...@gmail.com> wrote: > > > > But would it remove some blocks which contain data? > > > > On Tuesday, March 2, 2010, William Havey <bbha...@gmail.com> wrote: > >> A file system check of VxFS should be very quick. Read the > Intent Log records, write them out to disk, done. Do the > backup after fsck. > >> > >> On Sun, Feb 28, 2010 at 9:31 PM, Thomas Graham > <lktho...@gmail.com> wrote: > >> guys, I am using veritas cluster file system, and currently CFS is > >> marked as dirty and I have to take the whole FS offline to do fsck > >> scanning. Anyone know if there have any risk to hit inode if I do > >> backup during inode invalid situation? > >> > >> -- > >> Thomas G Lau > >> Tel: 93239670 > >> _______________________________________________ > >> Veritas-vx maillist - veritas...@mailman.eng.auburn.edu > >> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-vx > >> > >> > > > > -- > > Thomas G Lau > > Tel: 93239670 > > > > > > -- > Thomas G Lau > Tel: 93239670 > _______________________________________________ > Veritas-vx maillist - Veritas-vx@mailman.eng.auburn.edu > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-vx > _______________________________________________ Veritas-vx maillist - Veritas-vx@mailman.eng.auburn.edu http://mailman.eng.auburn.edu/mailman/listinfo/veritas-vx
