DSS on ESXi 4.1 - Slow RAID5 Reads?

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11-01-2010, 08:50 PM
npusnik

DSS on ESXi 4.1 - Slow RAID5 Reads?

Hi folks,

I'm running DSS v6 (lite) as a VM on ESXi 4.1.

Setup is as follows:
2x3GHz Xeons
12GB RAM
PERC 5i:
2x500gb SATA for VM Datastore's, RAID0, no read ahead, write back, 64kb block
3x1TB SATA RAID5, no read ahead, write back, 64k block

I've created a VM for DSS with the settings:
1 GB RAM
LSI Parallel:
8gb HD (installed to)

First, I tried formatting the datastore with an 8mb block size, and created a virtual hard drive of 1.8TB.

Results were:
50MB/sec write
3/4MB read

Next, I tried creating a datastore with a 1MB block size, created and added 8 256GB virtual hard drives under a software RAID0 array.

Results:
50MB/sec write
15MB read

Hmmmmmmmmmmmmmmmmmm

Any ideas on whats causing the slow reads?
11-01-2010, 09:06 PM
npusnik

File Copy results were done from a local client on a GB LAN.
11-01-2010, 10:26 PM
Gr-R

test with WB(writeback) off, and report back results.
11-01-2010, 10:31 PM
To-M

Actually I would test with it on for the LUN, also are you using Block IO or File IO?
11-01-2010, 10:54 PM
npusnik

I'm going to try using raw disk mapping as it looks to be a better way to present DSS with the array (since the LUN im carving from is local).
11-01-2010, 10:56 PM
npusnik

Quote:

Originally Posted by To-M

Actually I would test with it on for the LUN, also are you using Block IO or File IO?

This was just a simple test using SMB/CIFS share through a Windows 7 client (management box). Not sure how to set IO options (if they are available for this type of share?)
11-01-2010, 10:58 PM
Gr-R

Quote:

Originally Posted by npusnik

I'm going to try using raw disk mapping as it looks to be a better way to present DSS with the array (since the LUN im carving from is local).

misread your post....WB on RAID....
like 'To' says... try it on for the LUN.
11-02-2010, 01:44 PM
npusnik

Update:

Re-initialized the arrays, gave DSS raw access to the 1.8TB array - both virtual and physical RDM methods.

Results:
Write, 60-70MB/sec
Read 20MB/sec

I only have the option for Write Through or Write Back - and I'm not sure why those would effect reading from the LUN - but I'll change it next and see what the results are.
11-02-2010, 02:45 PM
npusnik

Another update:
Created an ISCSI volume using FILE I/O, mapped the target to my Win 7 management desktop

Results
100MB/Sec write
20MB/Sec read

I'm going to try to install Dell's OpenManager to see if there's something I'm not catching with the PERC's RAID5 array.