Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Thu, Jun 19, 2008 at 09:28:58PM +0200, Marcelo Azevedo wrote: > After placing the metadata on a different spindle (HD) , i was able to reach > almost close to native speed (1-2MB/s less) > > with metadata internal i was reaching tops around half of the native speed , > 37MB/s~ : > physical partition -> drbd -> ext3 > and > 63MB/s~ with physical partition -> ext3 > 61MB/s with metadata external, now this is true for another strong machine . > > This other machine has hardware RAID1 with two : > Cheetah T10 series, > 146GB ,Serial Attached SCSI > Interface Speed: 3Gb/s > Spindle Rotation Speed: 15,000 RPM > Performance: 10K > on an IBM 2G Xeon server with 2 dual cpu packages , each cpu with 4 cores . IBM > ServeRAID SCSI controllers > 4GB of ram > native speed -hardware raid1 -> physical partition -> ext3 is around 110MB/s > ( still isn't this a bit slow for this HD ? ) > hardware raid1 -> physical partition -> drbd -> ext3 - 101MB/s with > external metadata on a USB2 connected SATA HD 7,200 rpm > > now this is the crazy part - 8.3MB/s~ write speed ! with internal metadata , > and 150MB/s read speed.. > this test was repeated with bonnie , iozone and dd , all showed around same > numbers , > i mean why the huge jump from 8MB/s to 100MB/s when using external metadata , > and should this be STRESSED on the Docs or when starting the program that > putting the metadata on external media improves performance significantly? , > still i don't understand why i was able to reach only 8MB/s write speed on this > strong server , maybe because of the hardware raid1 underneath? http://www.drbd.org/users-guide/ch-internals.html#s-metadata -> internal meta data -> disadvantages "head movements" aka seek time. if you use internal meta data on the same single spindle, without a decent battery backed write cache, you want to configure a large-ish al-extents, so drbd meta data updates happen infrequently. -- : Lars Ellenberg http://www.linbit.com : : DRBD/HA support and consulting sales at linbit.com : : LINBIT Information Technologies GmbH Tel +43-1-8178292-0 : : Vivenotgasse 48, A-1120 Vienna/Europe Fax +43-1-8178292-82 : __ please don't Cc me, but send to list -- I'm subscribed