From mboxrd@z Thu Jan 1 00:00:00 1970 From: Edward Shishkin Subject: Re: Where to put the journal Date: Thu, 05 Aug 2004 21:31:33 +0400 Message-ID: <41126EF5.5080804@namesys.com> References: <410CCFCA.1030309@baldauf.org> <410E08F7.9020303@namesys.com> <411262DC.4070206@namesys.com> <411268D1.7000101@baldauf.org> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <411268D1.7000101@baldauf.org> List-Id: Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: =?ISO-8859-1?Q?Xu=E2n_Baldauf?= Cc: "Vladimir V. Saveliev" , Reiserfs List Xu=E2n Baldauf wrote: > Edward Shishkin wrote: > >> Vladimir V. Saveliev wrote: >> >>> Hello >>> >>> Xu=E2n Baldauf wrote: >>> >>>> Hello, >>>> >>>> I want to setup a Linux software RAID 5 over disks of different=20 >>>> speed with reiserfs on top. I know that the journal has to be=20 >>>> accessed frequently for comparably small accesses. That's why I'm=20 >>>> considering to "offload" the journal onto an extra partition on a=20 >>>> faster disk of the RAID set. >>>> >>>> Thus, the journal would not be protected by the RAID, but this is=20 >>>> not so important for me. >>>> >>>> Is this kind of reasoning sane? Would there be any speedup by=20 >>>> offloading the journal? >>>> >>> >> >> Hello. >> Unfortunately comprehensive results of journal relocation are obsolete >> as it was done at the beginning of mongo evolution. As I remember there >> were no any essential speedups. The only result of journal =20 >> relocation that >> was created by new mongo benchmark can be found here: >> http://thebsh.namesys.com/benchmarks/journal_relocation_to_NVRAM.html > > > Thank you, > > essentially, these numbers say that relocation provided a speedup of=20 > about 10% for write.=20 Note this is for data logging journal mode (mount option "data=3Djournal") Edward. > This surprises me a bit, because I expected a significantly smaller=20 > seek count for a write operation. Nevertheless, maybe I should run=20 > benchmarks with many small files for myself. :-) > >> >> Edward. > > > > ciao, > > Xu=E2n Baldauf. > >> >>> Person who did some tests on non standard journal is on vacation. He=20 >>> is expected to come back today. Maybe he remembers benchmark results, >> >> > > >