The default recordsize is 128K. So you are correct, for random reads performance will be bad as excess data is read. For Oracle it is recommended to set the recordsize to 8k. This can be done when creating the filesystem using 'zfs create -o recordsize=8k <fs>'. If the fs has already been created then you can use 'zfs set recordsize=8k <fs>' *however* this only takes effect for new files so existing databases will retain the old block size.
Hope this helps: Neil. qihua wu wrote: > Hi, All, > > We have an oracle standby running on zfs and the database recovers > very very slow. The problem is the IO performance is very bad. I find > the recordsize of the ZFS is 128K, and the oracle block size is 8K. My > > My question is: > When oracle tries to write a 8k block, will zfs read in 128K and then > write 128K. If that's the case, then zfs will do 16 (128k/8k=16 > )times IO as necessary. > > extended device statistics > > r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device > > 0.0 0.2 0.0 1.6 0.0 0.0 6.0 7.7 0 0 md4 > > 0.0 0.2 0.0 1.6 0.0 0.0 0.0 7.4 0 0 md14 > > 0.0 0.2 0.0 1.6 0.0 0.0 0.0 7.6 0 0 md24 > > 0.0 0.4 0.0 1.7 0.0 0.0 0.0 6.7 0 0 sd0 > > 0.0 0.4 0.0 1.7 0.0 0.0 0.0 6.5 0 0 sd2 > > 0.0 1.4 0.0 105.2 0.0 4.9 0.0 3503.3 0 100 ssd97 > > 0.0 3.0 0.0 384.0 0.0 10.0 0.0 3332.9 0 100 ssd99 > > 0.0 2.6 0.0 332.8 0.0 10.0 0.0 3845.7 0 100 ssd101 > > 0.0 4.4 0.0 563.3 0.0 10.0 0.0 2272.4 0 100 ssd103 > > 0.0 3.4 0.0 435.2 0.0 10.0 0.0 2940.8 0 100 ssd105 > > 0.0 3.6 0.0 460.8 0.0 10.0 0.0 2777.4 0 100 ssd107 > > 0.0 0.2 0.0 25.6 0.0 0.0 0.0 72.8 0 1 ssd112 > > > > > UC4-zuc4arch$> zfs list -o recordsize > RECSIZE > 128K > 128K > 128K > 128K > 128K > 128K > 128K > 128K > 128K > > Thanks, > Daniel, > ------------------------------------------------------------------------ > > _______________________________________________ > 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
