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Re: Openldap2.4.16 performance issue

----- Original Message -----
> From: "Dieter Kluenter" <dieter@dkluenter.de>
> To: openldap-technical@openldap.org
> Sent: Saturday, August 21, 2010 3:07:04 AM
> Subject: Re: Openldap2.4.16 performance issue

> "Singh, Devender (GE Capital, consultant)" <Devender.Singh2@ge.com>
> writes:
> > Hi Dieter,
> >
> >  Please find the below details:
> >
> > 1. hardware related
> >
> >    - type of storage - Simply SATA had disk attached.
> >
> >    - raid level, if any- No RAID
> >
> >    - file system of disk(s)- ext3 on LVm
> >
> >    - type of network, 100MB, 1G, 10G
> >
> >
> >
> > 2. is this host running on a virtual machine or on bare metal.
> >
> >    - if virtual machine, -Yes, OS installed on VM
> >
> >    -- what type ---Don’t know
> There is nothing suspicious, except for the virtual machine. Your
> really should carefully check layout and configuration of this VM, do
> not use virtual disks.

Hi Dieter,

Could you kindly explain what this means? I've been all over the inter-webs and I'm not finding anything concrete about OpenLDAP and VM's or Databases and VM's in general. The closest I came was about some database latency studies and some VMware propaganda.

We are about to launch a master and two replicas (utilizing delta-syncrepl) running in Ubuntu 10.04 on a VMware VSphere ESXi 4.0 cluster with four IBM x3650-M2's (2 Quad Nahalem and 64GB memory each) with virtual disks carved from NFS mounts to all of the VSphere servers in the cluster to facilitate HA and FT - by the VMware book.

(BTW, I took one of Howard's old posts to heart and we are following the Ubuntu playbook and we have purchased Canonical 24x7 support/maintenance. :-) )

We have had no problems with this environment in development and get better results than on bare metal with or without RAID. I know that it is recommended that the logs live on another "disk" from the database and RAID is frowned upon, but I have difficulty with a few points:

1) Separate, unprotected disks seems illogical. The last log and the BDB files are necessary to start BDB in slapd, correct? So, if you lose either disk, you're in trouble. Backups are ok, but daily seems too long a time. Seeing as we process new user accounts every 15 minutes, this would not be ideal for us.

2) RAID-1 I can understand having an issue on writes. But what about LUNs in FC from a NetApp 3140? Virtual disks on NFS in VMware? Both of these are in the best practices of both VMware and NetApp documentation.

3) 13-disk 7200RPM SATA RAID-DP (NetApp) is far faster than a single disk, dual diak or RAID-1, so why wouldn't you use SAN/NAS storage?

I seriously want to understand the VM concern as it pertains to OpenLDAP. I think more and more people are doing this very thing and will benefit from this discussion.

Our database is 86K+ DN's averaging about 40 attributes each. We've tuned the HDB cache to 768MB in a shared memory segment and the pertinent master slapd.conf file shows:

shm_key		100
cachesize	200000
idlcachesize	600000
dncachesize	400000
checkpoint	1024 15
# main database
index	objectClass	eq
index	cn	eq,sub
index	sn	eq,sub
index	gn	eq,sub
index	mail	eq,sub
index	uid	eq,sub
index	displayname sub,eq
index	memberUid	eq,sub
index	uidNumber	eq
index	gidNumber	eq
index	sambaSID	eq
index	sambaSIDlist	eq
index	sambaDomainName	eq
index	sambaPrimaryGroupSID	eq
index	sambaGroupType	eq
index entryCSN eq
index entryUUID eq
index	default	sub,eq

Replicas have identical indexes and shared memory usage. Basically, just running database population tests with full checking turned on, I get the following results:

Ubuntu 10.04.1 on all with OpenLDAP 2.4.21/BDB 4.7.25 (all generate 200-10MB log files):

IBM x3550 2-quad 5450 16GB, RAID-1 15K 73GB 3.0Gb/s SAS, 86K DN's - 30 minutes
IBM x3550 2-quad 5450 16GB, Single 15K 73GB 3.0Gb/s SAS, 86K DN's - 28 minutes
IBM x3550 2-quad 5450 16GB, 2-single 15K 73GB (db and logs on separate disks) 3.0Gb/s SAS, 86K DN's - 28 minutes
VMware guest 2-vCPU, 3GB memory, 100GB virtual disk on VMware NFS mount of 13-1TB 7200RPM SATA disks in NetApp 3140 - 4 minutes.

We can replicate to another VM in 9 minutes and two VMs simultaneously to the same 13-disk aggregate in 13 minutes. Aside from VM clock skew problems, I don't see the benefit of Bare Metal and I'm feeling pretty dumb at the moment.

Any insight from you, Quanah and/or Howard is humbly accepted and appreciated - I am here to learn. :-)

Thank you,

> -Dieter
> -- Dieter Klünter | Systemberatung
> sip: 7770535@sipgate.de
> http://www.dpunkt.de/buecher/2104.html GPG Key ID:8EF7B6C6