Hi Folks, Man pages of ZFS and ZPOOL, clearly saying that it is not good (recommended) to use some portion of device for ZFS file system creation. Hardly what are the problems if we use only some portion of disk space for ZFS FS ? or Why i can''t use one partition of device for ZFS file ststem and another partition of for some other purpose ? Will it cause any problems if i use one partition of device for ZFS and another partition for some other purpose ? Why all people are strongly recommending to use whole disk (not part of disk) for creation zpools / ZFS file system ? Your help is appreciated. Thanks & Regards Masthan --------------------------------- Want to start your own business? Learn how on Yahoo! Small Business. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20061207/4c79c22b/attachment.html>
On 07 December, 2006 - dudekula mastan sent me these 2,9K bytes:> Hi Folks, > > Man pages of ZFS and ZPOOL, clearly saying that it is not good > (recommended) to use some portion of device for ZFS file system > creation. > > Hardly what are the problems if we use only some portion of disk > space for ZFS FS ? > > or > > Why i can''t use one partition of device for ZFS file ststem and > another partition of for some other purpose ?You can.> Will it cause any problems if i use one partition of device for ZFS > and another partition for some other purpose ?No.> Why all people are strongly recommending to use whole disk (not part > of disk) for creation zpools / ZFS file system ?One thing is performance; ZFS can enable/disable write cache in the disk at will if it has full control over the entire disk.. /Tomas -- Tomas ?gren, stric at acc.umu.se, http://www.acc.umu.se/~stric/ |- Student at Computing Science, University of Ume? `- Sysadmin at {cs,acc}.umu.se
> Why all people are strongly recommending to use whole disk (not part> of disk) for creation zpools / ZFS file system ? One thing is performance; ZFS can enable/disable write cache in the disk at will if it has full control over the entire disk.. ZFS will also flush the WC when necessary, and if applications are waiting for an I/O to complete, this is typically a point where data must be flushed out. So I don''t expect much application performance gains here. There is a subset of SATA drives that do not handle concurrent I/O requests and staging I/Os through the cache can be a away to drive more data throughput in them. But for many devices the write cache is not a big performance factor. ZFS does some intelligent I/O scheduling and giving it entire disks allows that code to be more effective. Building pools with many slices from one disk, means more head movements and lost performance. -r