This post is more than 5 years old
1 Message
0
13558
June 5th, 2012 14:00
New Member to Group
Hey all,
We currently have a group with 3 PS6010's with 600GB 15k SAS drives in RAID 50 connected via 10GE. We just purchased a new PS6010 with 3TB 7.2k SAS drives. All members are on the latest firmware 5.2.2.
So we have been trying to decide if we wanted to add this new member to the same pool to take advantage of the APLB or Create a new pool for it.
So my question is twofold, can I mix spindle speeds in the pool, I know it was a no-no before but was unsure with the new "Fluid Data Technology".
If I can mix and bring this into the pool what is the turnaround time for APLB to balance when in starts seeing the latency? We are a College who sees large activity bursts at the registration periods before semesters and this only lasts a few days, so we were unsure if the APLB would react fast enough to this burst periods?
Any info would be appreciated.
DELL-Joe S
7 Technologist
•
729 Posts
1
June 6th, 2012 13:00
Q: Can I mix spindle speeds in the pool, I know it was a no-no before but was unsure with the new "Fluid Data Technology".
It is possible to mix drive technologies in the same pool, however, if you do put them in the same pool, the performance balancing will tend to move hot pages to the less busy array. There is a latency difference threshold that will determine when that happens. However, the new 6010 is larger by a fair amount compared to the existing 6010’s, so a larger proportion of the volume slices will reside on this member, so it will end up doing most of the work.
The other thing to consider is the iSCSI connections, more pools equals more connections, but this may not be issue if you are well below the max amount now (1024 per pool, 4096 up to 4 pools)
Overall, you are likely better off in a different pool and if something changes you can later merge them together.
If you haven’t seen this, review the “Dell EqualLogic PS Series Architecture: Load Balancer” which discusses this in greater detail: www.equallogic.com/.../DownloadAsset.aspx
Q: Turnaround time for APLB to balance when in starts seeing the latency?
APLB runs with a lower priority than the processing of application I/O. Every few minutes the APLB analyzes the latencies of the members in the pool and if any members have a higher latency then the lowest latency member(s), APLB will rebalance by moving high I/O to a less loaded member (with lower latency). This starts as soon as I/O begins and certain patterns of data access develop.
-joe
mphilli7823
8 Posts
0
June 6th, 2012 13:00
Dell-Joe S,
I am looking to do something similar however my two arrays are the ps6510 (48x 10K SAS RAID50) and a ps6110xs (7x SSD & 17x 10K SAS RAID-6 accelerated). Would it be advisable in my situation for me to put both of these members in the same pool?
mphilli7823
8 Posts
0
June 6th, 2012 13:00
Well, I am not an equallogic expert but I have been wondering the same thing as you recently, and it seems that the only constraint now is to not assign the same RAID level to members with different drive speeds. Take a look at the following doc.
www.equallogic.com/.../tr1027-tiered-storage.pdf
However given your situation and seeing as you need "guaranteed" performance for a short period of time, I think I would configure the volume that hosts your registration applications to prefer to live on the member with the faster drives. In your case this would seem to be one of the PS6010 with the 15K SAS drives. Also if you need even more performance you could reconfigure the RAID level on one of the 6010's to use RAID10. Let me know what you think....
DELL-Joe S
7 Technologist
•
729 Posts
0
June 6th, 2012 14:00
mphilli7823, hopefully I answered your question on your original post: en.community.dell.com/.../20118541.aspx
-joe