Very low performance issue

[Panchux]

Hi Zimbra Gurus, I'd tried to solve this problem myself reading this an other forums but I got no satisfactory results.

I have set up a mail server using a AMD Athlon 245 X2 CPU with 8gb of RAM (DDR3 1333mhz) and 3 hdds (1 SATA2 7200rpm 500GB for OS and 2 2TB SATA2 7200rpm for /opt directory creating RAID 1 software array) for 120 users. These users are mainly web users, the rest is using IMAP accounts and just 4 or 5 are using their accounts as POP.

The problem is that Zimbra has an intensive disk usage and it seems to be killing the RAID array and performance is really slow in peak hours.

What can I do to get a better performance without changing the whole server?

I'm planning to upgrade RAM to 12GB but I'm totally confident about a performance improvement.

Any ideas will be welcome. Thanks in advance,

Pancho

[j2b]

Could it be an option to separate servers/processes on different machines? Regarding MTA load here is interesting comment from LMStone Multi- server setup query. MailBox server runs logger service, which takes resources too. Do you use Software RAID or hardware RAID?

[Klug]

If you're running AV and AS on the server, search the forum about setting up a ramdisk for amavis temp directory.

[Panchux]

J2b, thanks for your quick response.
Unfortunately I'm using a software RAID. I can add a new server if the process is transparent to the user.

I have just marked the multi-server post for later reading. What I saw after a fast reading is the possibility to implement a RAM disk por antivirus. I've disabled antivirus services from the administration console but somehow is still running. TOP command shows it running.

Klug, How can I setup a RAM disk for antivirus? I know how to setup a ramdisk what I dont know is where do I tell the antivirus tu use it and btw how much space would it need.

Thanks to both of you,

Pancho

[Panchux]

Good news! I might have an HP Proliant DL360 G5 at my disposal. It has an Intel Xeon with 4 cores and 2 146GB 10k disks. It has only 2GB of RAM but I can upgrade it up to 16GB.

If you should install a mail server with this machine considering performance as the main goal how would you set it up?

Thanks for your time and knowledge,

Pancho

[j2b]

As it is pointed out in forums, Zimbra is quite intensive on write operations, rather than read. So you have to plan your RAID stack for this. Preferably it should be SAS fast disks and RAID 1 or RAID 10. Preferably quality hardware RAID with battery backup. As to my conclusion, most intensive tasks of Zimbra is AV and Logger. You then should plan or look more to separate intensive tasks on other servers with/without load balancing, or at least find workarround to easy such tasks to server. I have not experienced move from one server to multiserver, as we started our implementation from multiserver at the very begining. May be some one else can comment on this. But I plan to implement RAMDISK too, as it would decrease load and operation time on our MTA servers (separate from all the other stack). Googling just gave me interesting link: Howto Create A RAMDISK in Ubuntu / debian Linux |Linux and Microcontroller Tips
Again, my first link in post above directed you to issues of planning multiserver installation. In our case, we mostly separate each tasks: MTA, Mailbox (with logger), LDAP, Proxy for imap/pop, Separate proxy for web frontend - all on separate machines. But in your case, if you are going to run it on one physical server, you defenitely have to do tuning of your system.

[Panchux]

j2b, thanks for your comments. I can use both machines (actual and the Proliant) for an split domain configuration or to separate tasks. In both cases I don know how to achieve it. Maybe someone could point me in the right direction.

RAM disk will be implemented on both. What I don't know is how much space to asign to the RAM disk or where to set up AV to use it.

Again any ideas will be much appreciated,

Pancho

[Panchux]

Today I managed to create a RAM disk for amavisd usage and mount it through fstab.
Tomorrow I will see if there is a performance improvement and post back.

/dev/shm /opt/zimbra/data/amavisd/tmp tmpfs defaults,size=300m,mode=777 0 0

mail:~ # df -h
S.ficheros          Tamaño Usado  Disp Uso% Montado en
/dev/sda2             9,9G  3,0G  6,4G  32% /
devtmpfs              3,9G  152K  3,9G   1% /dev
tmpfs                 3,9G     0  3,9G   0% /dev/shm
/dev/sda3             447G   58G  367G  14% /home
/dev/dm-1             1,8T   52G  1,7T   3% /opt
/dev/shm              300M   44K  300M   1% /opt/zimbra/data/amavisd/tmp

Thanks to all,

Pancho

[j2b]

Nice to hear, you at least solved first step. It would be interesting to find out real gain of performance due to such changes.

Movement from single server to multiserver - pleas browse forum on this issue. As I've told already, I do not have experience on this.

Efficient amount of RAM or RAMDISK is probably the same, as you monitor your server - trial and errors. As it could be recreated very fast (still dependant of your disk system and can involve volume reconfiguration, if initial config will not suite your current needs) as necessary. And servers have not to be rebooted, I guess.

Split DNS - you only need this, if your both servers are in separate DMZs. If all of these servers are achievable via internet and in one DMZ, I do not think you have to bother about split DNS.

[Klug]

Originally Posted by j2b

Efficient amount of RAM or RAMDISK is probably the same

Not exactly : adding a ramdisk helps a lot on AV/AS.

As Amavis writes to disk (or ramdisk 8)) the messages, files, included files (in archives) and then read them, it hits a lot on the disk subsystem.

There's no need for a ramdisk on a mailbox server while having more RAM on it will help.

Originally Posted by j2b

Split DNS - you only need this, if your both servers are in separate DMZs. If all of these servers are achievable via internet and in one DMZ, I do not think you have to bother about split DNS.

If both servers are ZCS, there's no need to setup split DNS.
Just add the second server to the existing setup (master LDAP being on the first server) and put your users on the server you want 8)