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112565
CTIO status on Perc H710
Hi, i've recently purchased a new Dell R720 server with a H710 perc card fitted. I only have the 512Mb cache option so I was pleasantly surprised when I inserted an SSD that I was offered the ability to enable CacheCade using it.
This seemed to work (in that I could see the files accessed were written to the cache drive as they were used - checked by pulling it) despite the fact that the docs say only the 1Gb cards support it, but I'm not going to complain... Anyway, as I'm using quite a few SSDs in this box I wondered if CTIO was also now enabled by default.
I've configured the raid array using SSDs to be "no readahead" and "write through" as per the instructions but was wondering if there was a tool I could use to query if CTIO is actually enabled/being used. If not I'll put the settings back to "write back"
Thanks
John
DELL-Geoff P
990 Posts
1
August 24th, 2012 15:00
The documentation didn't reflect the new H710 series; it does support CacheCade.
Does this answer your iquiry?
Regards,
DELL-Geoff P
990 Posts
0
August 21st, 2012 09:00
Cut-through IO (CTIO) is an IO accelerator for SSD arrays that boosts the throughput of devices connected to the PERC controller. It is enabled through disabling the write-back cache (enable write-through cache) and disabling Read Ahead. If you have setup this way, then CTIO is enabled. If you use OpenManage, you should be able to see the controller settings.
Regards,
Stephan-thevalley
130 Posts
0
August 21st, 2012 12:00
Geoff,
Can you tell if the 512mb version of the h710 does support CacheCade or is this a bug ?
Stephan
DELL-Geoff P
990 Posts
0
August 21st, 2012 13:00
According to the documentation, the H710/512MB does not support CacheCade: http://dell.to/I4taBN
The 512MB or 1GB H710 models will support CTIO. Its either enabled or disabled by the steps provided. There is no setting in the controller to turn it on or off other than this.
Regards,
johnlister
14 Posts
0
August 21st, 2012 13:00
Thanks for replying. I have the settings as you describe, but there seems to be no way to determine if it is active or not. Performance testing hasn't really showed much, if anything it feels slightly slower - I've seen similar results on the web that by enabling the cache gave better benchmark results but that was on a raid 5 and I've got raid 10.
My concern was that as I only have a 512Mb card I shouldn't have Cachecade or CTIO, i was pushing my luck that as cachecade seems to work ctio might be enabled as well. This is with the latest firmware, etc
johnlister
14 Posts
0
August 21st, 2012 13:00
Its a nice bug to have :)
johnlister
14 Posts
0
August 21st, 2012 14:00
A quick play with MegaCli shows the following:
Product Name : PERC H710 Mini
Serial No : 26F01UZ
FW Package Build: 21.0.2-0001
...
Max Configurable CacheCade Size: 512 GB
Current Size of CacheCade : 111 GB
So I think we can assume CacheCade is enabled with a 512Mb card.
Also dumping the firmware log shows:
enableCTIO=1 enableSnapshot=0 enableSSC=1
under the MFC data, so I'm guessing CTIO is available as as well and should be active given the following cache settings on the logical drive:
Current Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU
btw, I think enableSSC means that cachecade(Solid State Cache) is enabled as well
Thanks
Stephan-thevalley
130 Posts
0
August 23rd, 2012 17:00
From support.dell.com/.../UG_PERC8_en.pdf page 93 :
The Dell PowerEdge RAID Controller (PERC) H710, H710P, and H810 cards
support CacheCade.
So no bug, but wrong info in other docs ?
johnlister
14 Posts
0
August 25th, 2012 01:00
Thank you, that does seem to be the case. In terms of the docs, the ones I can find for the plain H710 seem to indicate no CacheCade at 512Mb, but the H710P implies it is supported. I couldn't find the difference between the 2 cards - I'm guessing Professional or Performance and it relates to a bios option.
Thanks