Date: Wed, 1 Oct 2014 17:00:44 +0300 From: George Kontostanos <gkontos.mail@gmail.com> To: jg@internetx.com Cc: freebsd-fs@freebsd.org Subject: Re: HAST with broken HDD Message-ID: <CA%2BdUSyr9OK9SvN3wX-O4DeriLBP-EEuAA8TTSYwdGfcR1asdtQ@mail.gmail.com> In-Reply-To: <542C0710.3020402@internetx.com> References: <542BC135.1070906@Skynet.be> <542BDDB3.8080805@internetx.com> <CA%2BdUSypO8xTR3sh_KSL9c9FLxbGH%2BbTR9-gPdcCVd%2Bt0UgUF-g@mail.gmail.com> <542BF853.3040604@internetx.com> <CA%2BdUSyp4vMB_qUeqHgXNz2FiQbWzh8MjOEFYw%2BURcN4gUq69nw@mail.gmail.com> <542C019E.2080702@internetx.com> <CA%2BdUSyoEcPdJ1hdR3k1vNROFG7p1kN0HB5S2a_0gYhiV75OLAw@mail.gmail.com> <542C0710.3020402@internetx.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Oct 1, 2014 at 4:52 PM, InterNetX - Juergen Gotteswinter < jg@internetx.com> wrote: > Am 01.10.2014 um 15:49 schrieb George Kontostanos: > > On Wed, Oct 1, 2014 at 4:29 PM, InterNetX - Juergen Gotteswinter > > <jg@internetx.com <mailto:jg@internetx.com>> wrote: > > > > Am 01.10.2014 um 15:06 schrieb George Kontostanos: > > > > > > > > > On Wed, Oct 1, 2014 at 3:49 PM, InterNetX - Juergen Gotteswinter > > > <jg@internetx.com <mailto:jg@internetx.com> <mailto: > jg@internetx.com > > <mailto:jg@internetx.com>>> wrote: > > > > > > Am 01.10.2014 um 14:28 schrieb George Kontostanos: > > > > > > > > On Wed, Oct 1, 2014 at 1:55 PM, InterNetX - Juergen > Gotteswinter > > > > <jg@internetx.com <mailto:jg@internetx.com> <mailto: > jg@internetx.com > > <mailto:jg@internetx.com>> > > > <mailto:jg@internetx.com <mailto:jg@internetx.com> <mailto: > jg@internetx.com > > <mailto:jg@internetx.com>>>> wrote: > > > > > > > > Am 01.10.2014 um 10:54 schrieb JF-Bogaerts: > > > > > Hello, > > > > > I'm preparing a HA NAS solution using HAST. > > > > > I'm wondering what will happen if one of disks of > the > > > primary node will > > > > > fail or become erratic. > > > > > > > > > > Thx, > > > > > Jean-Fran=C3=A7ois Bogaerts > > > > > > > > nothing. if you are using zfs on top of hast zfs wont > even > > > take notice > > > > about the disk failure. > > > > > > > > as long as the write operation was sucessfull on one of > the 2 > > > nodes, > > > > hast doesnt notify the ontop layers about io errors. > > > > > > > > interesting concept, took me some time to deal with thi= s. > > > > > > > > > > > > Are you saying that the pool will appear to be optimal even > with a bad > > > > drive? > > > > > > > > > > > > > > https://forums.freebsd.org/viewtopic.php?&t=3D24786 > > > > > > > > > > > > It appears that this is actually the case. And it is very > disturbing, > > > meaning that a drive failure goes unnoticed. In my case I > completely > > > removed the second disk on the primary node and a zpool status > showed > > > absolutely no problem. Scrubbing the pool began resilvering which > > > indicates that there is actually something wrong! > > > > > > right. lets go further and think how zfs works regarding direct > hardware > > / disk access. theres a layer between which always says ey, > everthing is > > fine. no more need for pool scrubbing, since hastd wont tell if > anything > > is wrong :D > > > > > > Correct, ZFS needs direct access and any layer in between might end up = a > > disaster!!! > > > > Which means that practically HAST should only be used in UFS > > environments backed by a hardware controller. In that case, HAST will > > not notice again anything (unless you loose the controller) but at leas= t > > you will know that you need to replace a disk, by monitoring the > > controller status. > > > > imho this should be included at least as a notice/warning in the hastd > manpage, afaik theres no real warning about such problems with the > hastd/zfs combo. but lots of howtos are out there describing exactly > such setups. > > Yes, it should. I have actually written a guide like that when HAST was a= t its early stages. I had never tested it though for flaws. This thread started ringing some bells! > sad, since the comparable piece on linux - drbd - is handling io errors > fine. the upper layers get notified like it should be imho > > My next lab environment will be to try a DRBD similar set up. Although some tests we performed last year with ZFS on linux were not that promising. --=20 George Kontostanos --- http://www.aisecure.net
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CA%2BdUSyr9OK9SvN3wX-O4DeriLBP-EEuAA8TTSYwdGfcR1asdtQ>