[zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Albert Chin
Without doing a zpool scrub, what's the quickest way to find files in a filesystem with cksum errors? Iterating over all files with find takes quite a bit of time. Maybe there's some zdb fu that will perform the check for me? -- albert chin (ch...@thewrittenword.com)

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Richard Elling
On Sep 28, 2009, at 2:41 PM, Albert Chin wrote: Without doing a zpool scrub, what's the quickest way to find files in a filesystem with cksum errors? Iterating over all files with find takes quite a bit of time. Maybe there's some zdb fu that will perform the check for me? Scrub could be

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Bob Friesenhahn
On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums requires reading the data. So you simply need to read the data. This should work but it does not verify the redundant metadata. For

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Albert Chin
On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums requires reading the data. So you simply need to read the data. This

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Richard Elling
On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums requires reading the

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Tim Cook
On Mon, Sep 28, 2009 at 12:16 PM, Richard Elling richard.ell...@gmail.comwrote: On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Bob Friesenhahn
On Mon, 28 Sep 2009, Bob Friesenhahn wrote: This should work but it does not verify the redundant metadata. For example, the duplicate metadata copy might be corrupt but the problem is not detected since it did not happen to be used. I am finding that your tar incantation is reading hardly

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Albert Chin
On Mon, Sep 28, 2009 at 10:16:20AM -0700, Richard Elling wrote: On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Victor Latushkin
Richard Elling wrote: On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Richard Elling
On Sep 28, 2009, at 10:31 AM, Victor Latushkin wrote: Richard Elling wrote: On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - .

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Victor Latushkin
On 28.09.09 22:01, Richard Elling wrote: On Sep 28, 2009, at 10:31 AM, Victor Latushkin wrote: Richard Elling wrote: On Sep 28, 2009, at 3:42 PM, Albert Chin wrote: On Mon, Sep 28, 2009 at 12:09:03PM -0500, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Bob Friesenhahn
On Mon, 28 Sep 2009, Richard Elling wrote: In other words, I am concerned that people replace good data protection practices with scrubs and expecting scrub to deliver better data protection (it won't). Many people here would profoundly disagree with the above. There is

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Richard Elling
On Sep 28, 2009, at 11:41 AM, Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: In other words, I am concerned that people replace good data protection practices with scrubs and expecting scrub to deliver better data protection (it won't). Many people

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread David Magda
On Sep 28, 2009, at 19:39, Richard Elling wrote: Finally, there are two basic types of scrubs: read-only and rewrite. ZFS does read-only. Other scrubbers can do rewrite. There is evidence that rewrites are better for attacking superparamagnetic decay issues. Something that may be

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Robert Milkowski
Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums requires reading the data. So you simply need to read the data. This should work but it does not verify the

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Robert Milkowski
Robert Milkowski wrote: Bob Friesenhahn wrote: On Mon, 28 Sep 2009, Richard Elling wrote: Scrub could be faster, but you can try tar cf - . /dev/null If you think about it, validating checksums requires reading the data. So you simply need to read the data. This should work but it

Re: [zfs-discuss] Quickest way to find files with cksum errors without doing scrub

2009-09-28 Thread Bob Friesenhahn
On Mon, 28 Sep 2009, Richard Elling wrote: Many people here would profoundly disagree with the above. There is no substitute for good backups, but a periodic scrub helps validate that a later resilver would succeed. A perioic scrub also helps find system problems early when they are less