Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
> -----Original Message----- > From: drbd-user-bounces at lists.linbit.com > [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Ross > S. W. Walker > Sent: Thursday, January 11, 2007 7:48 PM > To: drbd-user at lists.linbit.com > Subject: [DRBD-user] DRBD and Direct Block IO > > > I am having some serious performance issues with a kernel module for > iSCSI Enterprise Target and drbd 0.7.21 on CentOS 4.4. > > The kernel module (source code listed below) basically takes a data > request issued over iSCSI translates it to a bio request that is then > carried out synchronously to the device below. > > When run against an MD/LVM/SD device I don't have any problems, I get > performance to be expected, but when run against a drbd > 0.7.21 device it > chokes down hard. For example when doing seq 64K block write direct to > device I can get 112 MB/s sustained, when I have drbd in the > middle that > throughput drops to 10 MB/s. > > Can anybody help explain this or point out a serious flaw in the code > below that would cause this. I would rather solve the problem (if it > can) then try to run version 8 beta in production (if it will > even solve > my problem). > > Thanks, > <snip code sample> I forgot to mention probably the most important piece of information, this drbd replica is currently running Standalone with no peer, so there is actually no replication happening at this time. -Ross ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.