Swapping

[Giorgi]

Hi there

I have some questions about swapping...

I am running 3gb RAM/Fedora 6/Core duo

1. I wonder what is: Max I/O Buffer Size is this RAM memory that litespeed can use to handle big files? So, if the limit is reached then litespeed will begin to dump in TMP directory and use it as RAM I guess?

2. What will later clean Swapping Directory ? how can I speed up cleaning TMP directory and is it recommended?

3. My server must handle large file uploads (650mb) what would you recommend? should I increase Max I/O Buffer Size or increase TMP directory size?

Thank you

[mistwang]

1. I wonder what is: Max I/O Buffer Size is this RAM memory that litespeed can use to handle big files? So, if the limit is reached then litespeed will begin to dump in TMP directory and use it as RAM I guess?

Yes,

2. What will later clean Swapping Directory ? how can I speed up cleaning TMP directory and is it recommended?

You do not need to. It should not have big impact on performance, and LSWS will avoid using it whenever possible.

3. My server must handle large file uploads (650mb) what would you recommend? should I increase Max I/O Buffer Size or increase TMP directory size?

Handling upload of 650mb file via HTTP then processing with PHP is not recommended. It is not efficient with too much overhead, better use FTP for file that big. If you have a few concurrent uploads, your server might be overloaded.

[mistwang]

3. My server must handle large file uploads (650mb) what would you recommend? should I increase Max I/O Buffer Size or increase TMP directory size?

In theory, larger I/O buffer should be better, but I think it does not matter much what parameter you tune for such large file. TMP directory size will grow automatically as long as there are enough free space.

[Giorgi]

Hm...

I have big problem, you see I am running Lsws enterprise on my file hosting site, it must accept that kind of files (650mb) upload via flash, but after about 1 hour of uploading I get IO error with filename

in my admin panel there is:

2007-10-16 22:31:10.800 ERROR [89.232.19.40:1509-0#APVH_www.mysite.com] out of swapping space while reading request body!

so what do you advice me to do?

[mistwang]

Please try setting "Max I/O buffer size" to "0", yes "zero", the swapping space will be limited by available disk space under /tmp.
Performance wise, you may not notice big difference unless the disk is too busy, server is disk I/O bound.
Use a dedicate disk for /tmp/lshttpd will help.

[Giorgi]

Originally Posted by mistwang

Please try setting "Max I/O buffer size" to "0", yes "zero", the swapping space will be limited by available disk space under /tmp.
Performance wise, you may not notice big difference unless the disk is too busy, server is disk I/O bound.
Use a dedicate disk for /tmp/lshttpd will help.

So I should consider increasing tmp partition?

[mistwang]

You don't have to. You can relocate the swap directory to somewhere else if you want.

http://www.litespeedtech.com/docs/we...l/#swappingDir

[Giorgi]

Originally Posted by mistwang

You don't have to. You can relocate the swap directory to somewhere else if you want.

http://www.litespeedtech.com/docs/we...l/#swappingDir

Now I am confused...

1. I thought that error I posted was caused because that I dont had enough space on tmp partition... is not that right?

2. and I have 3gb RAM, why litespeed wont use it at first place and then start to swap to tmp?

[mistwang]

Originally Posted by Giorgi

1. I thought that error I posted was caused because that I dont had enough space on tmp partition... is not that right?

No, when buffer memory was used up in the middle of a request, this error will occur. LSWS cannot switch from buffer memory to swap memory in the middle of a request. Some area can be improved in the future.

2. and I have 3gb RAM, why litespeed wont use it at first place and then start to swap to tmp?

If LSWS uses all 3gb RAM for the buffer, the server will become extremely slow. So, there is a configurable limit. once the limit is hit, it will start swap to tmp for new requests.

I think we will avoid buffer large request body in the buffer memory, instead, it will go straight to the tmp swap.

Even when swap is used, it is more likely that the swap file is cached in the memory, so the performance hit is minimum, and the OS kernel has more freedom to use system memory efficiently.

[Giorgi]

so I will need to increase tmp partition... I did so actually... increased it up to 10gb and progress went up to 83% then IO error occured again (before it only went up to 50%)

I dont understand why more than 10gb of tmp is needed to upload just 650mb file...

maybe something else is generating this error...

can Connection Timeout (secs) trigger that? I have it at 10 000 seconds... (650mb needs about 3.50 hours to upload)

I guess 10 000 seconds is hard limit, is there anyway to increase it further?