Tao Chen writes: > On 5/11/06, Peter Rival <[EMAIL PROTECTED]> wrote: > > Richard Elling wrote: > > > Oracle will zero-fill the tablespace with 128kByte iops -- it is not > > > sparse. I've got a scar. Has this changed in the past few years? > > > > Multiple parallel tablespace creates is usually a big pain point for > > filesystem / cache interaction, and also fragmentation once in a while. > > The latter ZFS should take care of; the former, well, I dunno. > > > > The purpose of zero-filled tablespace is to prevent fragmentation by > future writes, in the case when multiple tablespaces are being > updated/filled on the same disk, correct?
That and also there was a need for block reservation. Thus posix_fallocate was added (recently). > This becomes pointless on ZFS, since it never overwrites the same > pre-allocated block, i.e. the tablespace becomes fragmented in that > case no matter what. is fragmented the right word here ? Anyway: random writes can be turned into sequential. > > Also, in order to write a partial update to a new block, zfs needs the > rest of the orignal block, hence the notion by Roch: > "partial writes to blocks that are not in cache are much slower than > writes to blocks that are." > Fortunately I think DB almost always does aligned full block I/O, or > is that right? That's my understanding also. -r > > Tao > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
