Re: [zfs-discuss] Synchronous Mount?
> > Specifically, I was trying to compare ZFS snapshots with LVM snapshots on > > Linux. One of the tests does writes to an ext3FS (that's on top of an LVM > > snapshot) mounted synchronously, in order to measure the real > > Copy-on-write overhead. So, I was wondering if I could do the same with > > ZFS. Seems not. > > Given that ZFS does COW for *all* writes, what does this test actually intend > to show when running on ZFS? Am I missing something, or should not writes to > a clone be as fast, or even faster, than a write to a non-clone? Given that > COW is always performed, but in the case of the clone the old data is not > removed. > well, yes - for ZFS. But not the case with LVM snapshots. Doing the same (sync mount) on ZFS was just for comparing them on similar grounds. Anyways, I figured ZFS performs way better. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Synchronous Mount?
Hi Jason, > My company did a lot of LVM+XFS vs. SVM+UFS testing in addition to > ZFS. Overall, LVM's overhead is abysmal. We witnessed performance hits > of 50%+. SVM only reduced performance by about 15%. ZFS was similar, > though a tad higher. Yes, LVM snapshots' overhead is high. But I've seen that as you start increasing the chunksize, they get better (though, with higher space usage). So, you saw performance reductions as much as 15% with ZFS clones/snapshots. I'm curious to know what tests and ZFS config (# of snapshots/clones) you ran on. I ran bonnie++ and din't notice any perceptible drops in the numbers. Though my config had only upto 3 clones and 3 snapshots for each of them. > Also, my understanding is you can't write to a ZFS snapshot...unless > you clone it. Perhaps, someone who knows more than I can clarify. Right. I wanted to check if creating snapshots affected the performance of the origin FS/clone. Thanks, Prashanth > On 1/23/07, Prashanth Radhakrishnan <[EMAIL PROTECTED]> wrote: > > > > > > Is there someway to synchronously mount a ZFS filesystem? > > > > '-o sync' does not appear to be honoured. > > > > > > No there isn't. Why do you think it is necessary? > > > > Specifically, I was trying to compare ZFS snapshots with LVM snapshots on > > Linux. One of the tests does writes to an ext3FS (that's on top of an LVM > > snapshot) mounted synchronously, in order to measure the real > > Copy-on-write overhead. So, I was wondering if I could do the same with > > ZFS. Seems not. > > > > Thanks. > > ___ > > 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
Re: [zfs-discuss] Synchronous Mount?
> > Is there someway to synchronously mount a ZFS filesystem? > > '-o sync' does not appear to be honoured. > > No there isn't. Why do you think it is necessary? Specifically, I was trying to compare ZFS snapshots with LVM snapshots on Linux. One of the tests does writes to an ext3FS (that's on top of an LVM snapshot) mounted synchronously, in order to measure the real Copy-on-write overhead. So, I was wondering if I could do the same with ZFS. Seems not. Thanks. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Synchronous Mount?
Hi, Is there someway to synchronously mount a ZFS filesystem? '-o sync' does not appear to be honoured. Thanks, Prashanth ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Snapshot of a clone?
Hi, Is it possible to create snapshots off ZFS clones and further clones off those snapshots recursively? thanks, Prashanth ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
