Deleting user is too slow !!!

[ivo_toshev]

Hi there,

We are using Scalix 11.2 and this issue is true for all version of Scalix.
Deleting of single user ( 300 MB mailbox ) takes tens of minutes !!!! This operation is too slow !!! Really too slow ! For 2GB mailbox it takes more than 30-40 minutes.
This is just unbelievable.
Currently it was rare situation to delete users, but after 2 years , peaple coming and going, we decided to delete old and unused mailboxes, so to not waste space. We need to delete about 20 mailboxes, but with this speed for one day we did this just for 5 !

[Kris]

Isn't just your disk-speed the bottleneck here? When you delete a user, it's mailstore is also deleted. Deleting a user here doesn't take that long..

[ivo_toshev]

No, its definetly not the disk speed.

[mikevl]

Over quite a number of servers that we support I have personal experience that deleting a 2+GB takes 3 - 5 minutes.

Can you please confirm that if you run top while doing a user delete that the CPU remains at less than 20.0%wa, if you run iostat -k -d sda sdb sdc sdd 2 (or whatever disks you have) what sort of figures do you get?

What is your server configuration? Memory, Processor(s), disks

Mike

[ivo_toshev]

Hm... the wa is between 40 and 50 %?

and the output of iostat shows:
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
md0 130.86 40.95 72.92 964117496 1716896684

Why could i have such big WA % ? i have two 250GB IDE hdd in mirror. ?!

[mikevl]

Hi

IDE drives are not known for their extreme preformance. In a RAID1 configuration gives a slight performance hit (but not as much as RAID5).

Scalix is I/O based, dosen't require much CPU or memory relative other messaging software but I/O is important.

Of all operations deleting a user is among the most intensive, there are a few others like indexing, omscan to name but a few. These may take a long time to run. If a user mas deletes a buch of emails may also cause some delay.

for general usage your I/O configuration may be limited to 10 - 20 users

Mike

[ivo_toshev]

So your advise is to switch to SATA in RAID5 mode ?

[mikevl]

SATA is better.

RAID5 is the worst configuration of all. It has very terible Write performance, especially when doing simultaneous read write operations.

How many users do you have?

We have fast RAID edition SATA drives handeling up to 100 users

If you have more users then you may need additional spindles for /var/opt/scalix/nn/s/tmp and some other diectories

viewtopic.php?p=42485

This configuration did not work so well

Mike

[ivo_toshev]

Well... what you mean under RAID SATA ? If it is not RAID1 or RAID5 then what it is ?
It is very strange, because our Exchange 5.5 server runs just on one 160GB IDE and serves 80 Users without lack of performance. The Scalix Server now serves about 50 users and we have trouble with performance.

It seems that using file system for store has some drawbacks against SQL base.

[mikevl]

Hi yes there are many differences between Excahnge and Scalix an ther system requirements.

1) Exchjange requires masses of memory. Scalix does not. (unless you use SWA a lot)

2) Exchange uses ore CPU. Scalix is not CPU intensive

3) Exchange is easy on disks Scalix is disk intensive. The main difference here is that with Exchange you suffer from both disk fragmentation and database fragmentation with both impact on performance over a period of time. The performance of Scalix is consistant over a long period of time (set and forget) but has more stringent requirements from the outset.

for your setup we have a number od similar clients in the 50 - 100 users bracket. We have found that SATA and especially SATA2 is adequate for your enviornment. In either a RAID1 or RAID1+0 arrangement. RAID1+0 is better but a good number survive very happily on SATA2 RAID1.

In out situation we have one client of 50 users with 60% of them have mailboxes over 2Gb, some well over, on SATA this works well for them.

The requirements for running MAPI are a LOT less than if the client workstations are running an IMAP client or SWA. If all your users run IMAP then you may wish to consider RAID1+0.

As we do support some Exchange servers in a seperate part of our business I can say that Scalix runs 24 x 7 x 365 without outage. even for OS upgrades (except the kernel).

If you employ LVM snapshot for backing up then your server can be available for use 24 x 7. You can get as many backups a day as you wish to have. We have more than one client who are doing backups (RSYNC) once an hour or more without interruption to users.

Hope this helps

Mike