ML350 G6 too too slow

[Pepe Rodriguez]

I must verify first if the controller has any battery installed. And yes I have enabled write cache

[Pepe Rodriguez]

Hello everybody,

I run the ADU and you can find attached file results.

Could someone give it a read and look for anything wrong, I can't see nothing so bad for such low speed.

Thank you,
Pepe

[Michael A. McKenney]

The problem is RAID 5 parity writes. The controller has three functions: read, write, parity calculation. The problem with RAID 5 is parity calculations and writes. If your controller spends 70% writing data, it has to calculate parity for each of those writes for fault tolerance and redundancy. This can really slow down your arrays. This is how RAID 5 works. They did RAID 5 in the past because disks were slow and very expensive. Now with large inexpensive SAS drives, RAID 5 does not really make sense from a performance point of view.

I never use RAID 5 any more on production servers. It is too slow for writes. When you create or modify a file it is a write. Moving data from an old server to a new server with RAID 5 can be painful. I only use RAID 10 on production servers. If I need more space, I get a SAN and do RAID 10. I rather sacrifice about 5% read performance to gain write performance.

[Pepe Rodriguez]

I don't know why I can't upload the zip file with the diagnostics results.

[Michael A. McKenney]

You could try installing the battery and upgrading the cache? Is their any cache on it? Without the battery, your cache could be disabled it would help performance.

[SMR]

Write cache can now be enabled on new gen smart array controllers without the battery requirement, it does however pose a risk of data loss upon power failure, however, for testing purposes I suggest you enable it (you will be warned of the risk of enabling it without a battery backup) and then if you wanna keep it for production, buy the battery backup.

[Pepe Rodriguez]

The write cache is enabled actually and reading the diagnostics results I think it has battery installed already.

[Michael A. McKenney]

If you can, put another set of 4 disks on in RAID 10 and test performance. Crack open the server, check the battery is connected and it has a cache module. See what size the cache is. In the past, I upgraded 128 MB cache to 512 MB and saw a huge difference.

[Pepe Rodriguez]

I will open and check for the battery, the diagnostics utility saids it has 512MB of cache.

How can I upload the result file? I do select the file to upload and the file name appears next to the button, but when I push Submit, the screen goes blank and the message is not sent, if I go back the file is unselected and if push submit again the message is sent but without the attached file.

[Michael A. McKenney]

Try setting this site as trusted.