VMware, LVM and Raid information needed

[toni31]

Hi,

i need to know how to plan hardware requirements when using Scalix as a virtual machine in VMware Server. first about 80 users will connect, afterwards again about 220 users. Currently the evaluation server is installed under VMware Server 1.4 on AMD643000 with 1.5 GB RAM. the harddrive is virtual and not flat. Has someone used the option "physical hdd" in VMware Server? i think it is not recommended by Vmware, anyway, access via webmail only with one user is really slow.
Can i use LVM for backup? Is there any significant improvement by using a RAID 10 in the host machine? i have no experience in setting up a software raid in Linux, but could it be advisable in this configuration?

Thanks
Toni

[mikevl]

Hi

Hmmm lots of quizes

first about 80 users will connect, afterwards again about 220 users.

220 may be a few to many users for VMware Server

under VMware Server 1.4 on AMD643000 with 1.5 GB RAM. the harddrive is virtual and not flat. Has someone used the option "physical hdd" in VMware Server? i think it is not recommended by Vmware, anyway, access via webmail only with one user is really slow.

Yep. VMWare server gives a 30% hit on Disk speed. For 220 users you will need a RAID 1+ 0 SAS array anyway. Especially if you are using SWA on more than 20 accounts simuntaneously

Can i use LVM for backup? Is there any significant improvement by using a RAID 10 in the host machine? i have no experience in setting up a software raid in Linux, but could it be advisable in this configuration?

Yes we use LVM in ALL our installations. However you must understand RSYNC produces a bit of a disk hit also. Do NOT use Linux RAID that also can produce issues. A high quatilt HW RAID controller is best, your company depends on it.

Although some companies use VMWare as their choice (we have some clients also using VMware) we would not recommend this.

Mike[/quote]

[toni31]

Thanks for your answer,


That's really disappointing because of the hdd-performance in VMware.

In your answer i figured out that the SWA is mostly hddspeeddepending. What's about connecting only via imap client like thunderbird? Admin Guide: "Can handle 850 concurrent logins on 4 GB memory" (recommendation for swa AND imap). my focus is more the same performance using imap or swa than the number of users.

Could this be handled without enormous hardware investigations? btw: currently our mailserver is a P3, handling 80 users quite perfect.

thank you

[Alik]

We were using Vmware Server (Free) not ESX for 100 Users and are now back to real hardware. The performance was more than bad. I would like to try it with ESX Server and powerfull Storage.

[mikevl]

Hi

We have some sites on ESX as well. Its no better.

This may work for up to 30 - 50 users OK, at a pinch but over that well?????

I see that on some of our bare metal sites with 250 users active that that the RAID10 works hard. Not excessive but it is working. A 30% hit on this would be catastrophic.

VMWare also seems to create some latency in general responce times. I have not looked into why this happens, but it seems to be.

Our installation is only 7 users with 5 active on a Quad Xeon with 8GB RAM and VMWare and it is barely enough at times to keep up. But I must admitt its great for us as Scalix parteners as we can do many experiments on our working installation and if we crash it then theres alwats restore from snapshot. VMWares only saving grace. Clustering in VMWare is a disaster. Again great for testing configurations.

Just a few thoughts

Mike

[mikevl]

Hi toni31

SWA & IMAP are the most disk intensive operations of all. If you look through the litrature you will find quotes that say that Scalix can handel up to / more than 5000 users on a Dual Xeon server. This is true. With 4Gb RAM and a good disk array this would be easy meat. IMAP SWA exercise the disk and to some extent the processor more than Outlook does. The disk by quite a margin.

In our early days of computing, we started operations in 1990 we tried to save costs on hardware, it didn't really produce excellent results. Thats when hardware was REALLY expensice US$14,000 for a Pentium 75, 512Mb RAM and a 36Gb SCSI disk. Well that sort of money will now by you the earth. Scalix does not require much CPU at all Memory requirement are small as well. You can run more that 5000 Outlook users on the same ammount of RAM that is required for one person using Windows VISTA !!!!! But Scalix does require good I/O for 200 users and up. Good disks, godd configuration (as per the Release notes www.scalix.com/documentation) and a good hardware controller.

Releases admins from the added cost of taking prozac

Mike

[jhamill]

Hi,

i need to know how to plan hardware requirements when using Scalix as a virtual machine in VMware Server. first about 80 users will connect, afterwards again about 220 users. Currently the evaluation server is installed under VMware Server 1.4 on AMD643000 with 1.5 GB RAM. the harddrive is virtual and not flat. Has someone used the option "physical hdd" in VMware Server? i think it is not recommended by Vmware, anyway, access via webmail only with one user is really slow.
Can i use LVM for backup? Is there any significant improvement by using a RAID 10 in the host machine? i have no experience in setting up a software raid in Linux, but could it be advisable in this configuration?

Thanks
Toni

if you remove vmware from your picture, we moved from a LVM running raid 1+0 on an IBM blade server to an iScsi attached storevault (same server). The performance improvement was significant. Outlook opened much faster, changing sub folders was also greatly improved in terms of access times.

we had also moved the scalix temp folder to a ram disk before moving to iScsi as this was a real bottleneck. you could type ls in the tmp folder in a shell and wait 45 seconds before seeing anything. ram disk made a big difference to performance as well. however iscsi for tmp and main data store is very good.

[toni31]

thanks for your posts,

so i think using vmware it's not a good idea.
that brings me to backup my scalix. a scalix tech advises me to use lvm, which only needs seconds for a snapshot. i haven't got time to inform me about lvm yet. what i need is simple backup procedure for configuration and mails too. Can that be done by lvm or do i have to use SEP?

[mikevl]

Hi

LVM is the preferred method for getting backups of the entire message store. Using LVM you can do a daily TAR of the message store. More imoprtatantly you can use LVM to rsync the message store to a backup location multiple times a day. Some of our clients do this sub hourly. Its depends how mission criticle your mail is to your company. Thie best thing about LVM is it allows all this to happen without interruption to the users who will be blissfully unaware thath backups are hapening in the background.

However LVM snapshot technology is an OS install time decision. You either choose to provision for it when you install the OS or not.

Other backup methods include shutting down Scalix to get a message store back for the duration of the backup which could be several hours. Or using sxmboxexp to get individual mailbox (bricklevel) backups).

Having a tar or rsynced backup of the message store helps greatly should you have a hardware failure of any kind. In that event you can install a fresh OS, install Scalix out of the box and restore the tar or rsync file back over the new message store and in a very short time have a working server again.

This sort of functionality is not offered by proprietry systems to the same extent. Or I might add by any other linux based email system. This is due to the nature of the Scalix message store.

Mike

[obrodkin]

I am in virtual crowd too. Here is my HW:

Supermicro rackmounted server with 2x intel 5130 8GB RAM
Zero channel RAID card to support internal HW RAID10 6x Seagate SATA ES drives (250GB) and LSI RAID SAS card to support external Promise J300 box with 12 SATA/SAS drivers. Sounds plenty beef, but Scalix runs just ok, not snappy as I would expect.

Host OS is SLES10 with vmware on top, running Scalix as a guest (SLES 10) and file server (2nd guest). Not that I can see vmware impact on Scalix performance - we just have 20 users. But I think my setup is rather complex (with multiple layers of LVM). So after reading the post I will consider to downgrade scalix to bare metal (run it on the host OS) and use Xen to host the file server.

Forgot to mention that vmware runs with bdwrapper library so the guests have direct access to the host LVM volumes.

Oleg B

[toni31]

hi obrodkin,

i didn't understand your choice to downgrade scalix, when you say that you cannot see an impact on scalix performance?
btw: can you state that using a physical disk in a vmware guest speed up disk performance,should be,?
i've heard that vmware doesn't recommend that, but tested it never.

bye

[obrodkin]

toni,

To your question, I've never tested flat file vs physical device access speed, since my /var/opt/scalix is over 50GB and I thought it was too much for the flat file.

At this point, the only thing vmware offers me is availability. I can have another instance of OS+ scalix w/out need for extra HW. dwrapper is not vmware tool and need to be recompiled and tested with new OS every time I upgrade. Otherwords, pain. Plus LVM shows some weired glitches when has been accessed directly from vmware guest. By having all its data in one place, scalix does offer an easy route for migration to a new server: install OS, scalix and move /var/otp/scalix.

Xen, on the other hand, does natively provide access to physical devices, and is less CPU demanding. So I've figured out that I can run #1 instance of Scalix on the host and #2 - on XEN. Plus #3, my file server - Openfiler, as Xen image too. When times come to update, I will install new scalix on #2, test it, and after a while commit again to #1.

My production environment is SLES, so XEN dealing is relatively easy.

Your thoughts...

[toni31]

After running scalix on vmware server since two weeks, i have to say that mostly everything is doing well.
The only problem that occured a little bit too often is om 3433 the open container reference provided is invalid. After that most of the time mailbox isn't showing any new items anymore.

But is that owed by vmware? So far i don't know.

my configuration again:
currently 43 Premium users and 41 normal users. around 1500 mails a day, no antispam on scalix, clamav installed. Thunderbird as IMAP-Client, swa will be used by only a couple of users in future.
HW:
Dual Xeon 1,8, 3 SAS-HDDs + 1 Hotspare SAS-Raid 5, 10 GB Ram
Host SLES 10.1
VM: SLES 10.1, max. RAM of VMware (ca. 3,6 GB), 150 GB flatfile

In the next two weeks a dnsserver and a separate domain controller will be moved to this machine.
Hope there's no deep impact to scalix.

[obrodkin]

so your scalix /var/opt/ is in the flat file as well?

Re: DNS, i have 20 users and switched from BIND9 (what a headache) to dnsmasq - DHCL and DNS. Really easy to install and so far pretty reliable.

[toni31]

Everything is running in this 150 GB flat vm.
i followed the scalix manual for partitioning, i think /var has got 120 GB of size.

Bye
Flep