Date: Sat, 23 Jan 2010 10:10:54 -0500 From: jhell <jhell@DataIX.net> To: Alexander Leidinger <Alexander@leidinger.net> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, Artem Belevich <fbsdlist@src.cx> Subject: Re: Setting "zfs_arc_max" value in FreeBSD 8. Message-ID: <alpine.BSF.2.00.1001231002090.4905@pragry.qngnvk.ybpny> In-Reply-To: <20100123102513.00001f67@unknown> References: <7f14551c1001190119x46c6b04dx2362cd1252f0d81@mail.gmail.com> <hj3v0i$i2p$1@ger.gmane.org> <7f14551c1001190216w49814186n1ada2b721380502b@mail.gmail.com> <4B55C5A6.2020109@DataIX.net> <20100120111433.25801pnmhrxnirok@webmail.leidinger.net> <ed91d4a81001220847v15e26830la2d51479c3d104e1@mail.gmail.com> <alpine.BSF.2.00.1001222123400.3696@pragry.qngnvk.ybpny> <20100123102513.00001f67@unknown>
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On Sat, 23 Jan 2010 04:25, Alexander@ wrote: > On Fri, 22 Jan 2010 21:39:48 -0500 jhell <jhell@DataIX.net> wrote: > >> >> On Fri, 22 Jan 2010 11:47, fbsdlist@ wrote: >>>>> Anyone know if it is adjustable on a system with 1024MB of ram ? >>>>> Is this just being auto calculated by some other value ? >>> >>> You may want to make sure that vm.kmem_size is set to a value much >>> larger than vfs.zfs.arc_max. Default value may be too small to allow >>> such a large ARC. >>> >>> On a side note, I'm not sure that ZFS is a good match for system >>> with only 1G of RAM. By trial and error on my box with 8G or memory >>> I've figured out that I need to set arc_max ~1G below physical >>> memory size to avoid lockups under load. YMMV. >>> >> >> ZFS on this box with 1G has been quite enjoyable actually. With the >> settings I have posted I have not had any lockup on stable/7 and no >> sudden freezes or waits for transfers. So this entirely thus far has >> been a godsend. I had even put this thing through some of the >> tortures that others have posted to the list and not come up with the >> same results but better. There is obviously a lot of variables in >> this between hardware and configurations used so the results are >> minimal in comparison. With ZFS in place on this machine it performs >> a little bit under specs for the hardware but I wouldn't expect >> anything less for such a file-system. > > You may want to switch to fletcher4 checksums. This is the default in > Solaris and 8.0 now. I didn't merge this change to 7-stable as I didn't > took the time to analyze if the change for the default has some unwanted > implications for existig pools. > I will do this and report back with any differences that I find. As for your previous email that arrived I believe after this one, Thank you for your replies I appreciate the feedback. > I have a 9-current box with 1GB RAM and ZFS which shows the slow-down > after some hours of running (and doing things) too. It would be good to > make a list of OS versions and if there are slowdowns or not (anyone > with time out there to have a look at the mails and get this info out > of the mails / people?). Maybe it is related to changes not in ZFS... > > Bye, > Alexander. > Is there any recommendations from anyone ? so there is a basis for what can be tested from. (unixbench|iozone|others) in comparison to the same results version to version ? Thanks -- jhell
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