Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 03/12/2013 15:06, Gerald Brandt wrote: > Anybody have an idea whats happened (see below)? The iSCSI and NFS load are both KVM images (iSCSI is LVM based). > > Gerald > > > ----- Original Message ----- >> From: "Gerald Brandt" <gbr at majentis.com> >> To: drbd-user at lists.linbit.com >> Sent: Saturday, November 30, 2013 11:00:20 AM >> Subject: [DRBD-user] DRBD with iSCSI vs NFS issue >> >> Hi, >> >> I've been running DRBD on my servers for quite some time on some >> servers at a clients (a little over a year with this client, I >> believe). I've been exporting drbd0 as iSCSI for the entire time. >> Write tests over GigE (1B block size, sequential write) gives me an >> everage of 118MB/s. Very good. >> >> Last week, I switched drbd0 from iSCSI to NFSv3 exports. >> >> Performing the same test (I use XenServer Performance VM tool), I get >> very strange behaviour. atop shows an average write speed of ~35 >> MB/s. The Perf Tool shows 117-118 MB/s, with drops down to 0MB/s. >> There are a lot of drops, and the average via the tool equals what >> atop shows. >> >> If I remove the secondary, performance via NFS jumps and stays at >> 117-118 MB/s. >> >> The underlying DRBD config has not changed at all. >> >> Why am I seeing the difference between iSCSI exports on drbd0 vs NFS >> exporst on drbd0, only when the secondary is attached? >> >> Gerald Hi I have a similar issue (look for my recent post), except my issue causes load on my nfs clients to climb under lots or read/writes, I have lowered the impact now by adjusting the nfs mount options. According to the research I have done the slower speeds of nfs are just the nature of the nfs server due to it being a "shared" file system where as iscsi is dedicated to a single hosts read/writes. Thank you, Mark Adrian Coetser