Afternoon, In order to test my storage I want to stop the cacheing effect of the ARC on a ZFS filesystem. I can do similar on UFS by mounting it with the directio flag. I saw the following two options on a nevada box which presumably control it: primarycache secondarycache But I?m running Solaris 10U4 which doesn?t have them -can I disable it? Many thanks Rob | Robert Brown - ioko Professional Services | | Mobile: +44 (0)7769 711 885 | -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20090128/2e1cb86d/attachment.html>
Richard Elling
2009-Jan-28 17:35 UTC
[zfs-discuss] Is Disabling ARC on SolarisU4 possible?
Rob Brown wrote:> Afternoon, > > In order to test my storage I want to stop the cacheing effect of the > ARC on a ZFS filesystem. I can do similar on UFS by mounting it with > the directio flag.No, not really the same concept, which is why Roch wrote http://blogs.sun.com/roch/entry/zfs_and_directio> I saw the following two options on a nevada box which presumably > control it: > > primarycache > secondarycacheYes, to some degree this offers some capability. But I don''t believe they are in any release of Solaris 10. -- richard> > But I?m running Solaris 10U4 which doesn?t have them -can I disable it? > > Many thanks > > Rob > > > > > *|* *Robert Brown - **ioko *Professional Services *| > | **Mobile:* +44 (0)7769 711 885 *| > * > ------------------------------------------------------------------------ > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >
Nathan Kroenert
2009-Jan-28 22:23 UTC
[zfs-discuss] Is Disabling ARC on SolarisU4 possible?
Also - My experience with a very small ARC is that your performance will stink. ZFS is an advanced filesystem that IMO makes some assumptions about capability and capacity of current hardware. If you don''t give what it''s expecting, your results may be equally unexpected. If you are keen to test the *actual* disk performance, you should just use the underlying disk device like /dev/rdsk/c0t0d0s0 Beware, however, that any writes to these devices will indeed result in the loss of the data on those devices, zpools or other. Cheers. Nathan. Richard Elling wrote:> Rob Brown wrote: >> Afternoon, >> >> In order to test my storage I want to stop the cacheing effect of the >> ARC on a ZFS filesystem. I can do similar on UFS by mounting it with >> the directio flag. > > No, not really the same concept, which is why Roch wrote > http://blogs.sun.com/roch/entry/zfs_and_directio > >> I saw the following two options on a nevada box which presumably >> control it: >> >> primarycache >> secondarycache > > Yes, to some degree this offers some capability. But I don''t believe > they are in any release of Solaris 10. > -- richard > >> But I?m running Solaris 10U4 which doesn?t have them -can I disable it? >> >> Many thanks >> >> Rob >> >> >> >> >> *|* *Robert Brown - **ioko *Professional Services *| >> | **Mobile:* +44 (0)7769 711 885 *| >> * >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> zfs-discuss mailing list >> zfs-discuss at opensolaris.org >> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >> > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss-- ////////////////////////////////////////////////////////////////// // Nathan Kroenert nathan.kroenert at sun.com // // Systems Engineer Phone: +61 3 9869-6255 // // Sun Microsystems Fax: +61 3 9869-6288 // // Level 7, 476 St. Kilda Road Mobile: 0419 305 456 // // Melbourne 3004 Victoria Australia // //////////////////////////////////////////////////////////////////
Thanks Nathan, I want to test the underlying performance, of course the problem is I want to test the 16 or so disks in the stripe, rather than individual devices. Thanks Rob On 28/01/2009 22:23, "Nathan Kroenert" <Nathan.Kroenert at Sun.COM> wrote:> Also - My experience with a very small ARC is that your performance will > stink. ZFS is an advanced filesystem that IMO makes some assumptions > about capability and capacity of current hardware. If you don''t give > what it''s expecting, your results may be equally unexpected. > > If you are keen to test the *actual* disk performance, you should just > use the underlying disk device like /dev/rdsk/c0t0d0s0 > > Beware, however, that any writes to these devices will indeed result in > the loss of the data on those devices, zpools or other. > > Cheers. > > Nathan. > > Richard Elling wrote: >> > Rob Brown wrote: >>> >> Afternoon, >>> >> >>> >> In order to test my storage I want to stop the cacheing effect of the >>> >> ARC on a ZFS filesystem. I can do similar on UFS by mounting it with >>> >> the directio flag. >> > >> > No, not really the same concept, which is why Roch wrote >> > http://blogs.sun.com/roch/entry/zfs_and_directio >> > >>> >> I saw the following two options on a nevada box which presumably >>> >> control it: >>> >> >>> >> primarycache >>> >> secondarycache >> > >> > Yes, to some degree this offers some capability. But I don''t believe >> > they are in any release of Solaris 10. >> > -- richard >> > >>> >> But I?m running Solaris 10U4 which doesn?t have them -can I disable it? >>> >> >>> >> Many thanks >>> >> >>> >> Rob >>> >> >>> >> >>> >> >>> >> >>> >> *|* *Robert Brown - **ioko *Professional Services *| >>> >> | **Mobile:* +44 (0)7769 711 885 *| >>> >> * >>> >> ------------------------------------------------------------------------ >>> >> >>> >> _______________________________________________ >>> >> zfs-discuss mailing list >>> >> zfs-discuss at opensolaris.org >>> >> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >>> >> >> > >> > _______________________________________________ >> > zfs-discuss mailing list >> > zfs-discuss at opensolaris.org >> > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > > -- > ////////////////////////////////////////////////////////////////// > // Nathan Kroenert nathan.kroenert at sun.com // > // Systems Engineer Phone: +61 3 9869-6255 // > // Sun Microsystems Fax: +61 3 9869-6288 // > // Level 7, 476 St. Kilda Road Mobile: 0419 305 456 // > // Melbourne 3004 Victoria Australia // > ////////////////////////////////////////////////////////////////// >| Robert Brown - ioko Professional Services | | Mobile: +44 (0)7769 711 885 | -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20090212/fa44dbb9/attachment.html>