This post is more than 5 years old
50 Posts
2
3029
FAST VP SATA usage and relocation rate
So we are FINALLY cruising along in our VMAX 20K testing but i'm a little concerned with FAST VP SATA usage. I’ve been testing a pretty heavy SQL workload over the past week from two servers in FAST VP. If I run both at the same time it will peak to about 48K IOPS. In our configuration we have 16 EFD in R5, 388 10K FC in R5, and 280 SATA in R6. The SATA is broken up into two disk groups due to using some for the vault, but both SATA disk groups are in the same pool. My concern is when I put a storage group in a policy that allows 100% on any tier it doesn’t seem to use FC much at all, although it does put a small percentage in EFD. In fact I moved a SG entirely to FC and FAST VP demoted down to SATA pretty quickly even while I was running jobs. I also tried binding to FC since the SG's were origionally binded to SATA but with the “Allocate by FAST policy” enabled in 5876 it will put new writes to the tier that it thinks it should where in 5875 all new writes went to whatever teir it was binded to. My assumption from reading "Implementing Fully Automated Storage Tiering for Virtual Pools (FAST VP) for EMC Symmetrix VMAX Series Arrays Technical Notes" would be I/O in FC should be higher than SATA I’m seeing 6K IOPS in two SATA Disk Groups for a total of 12K in SATA and only 600 IOPS in the FC. SATA seems to be handling it fine now, but we only have 24TB out of 510TB allocated so I’m worried what will happen with this SATA tier once we go live and start migrating a bunch of hosts. Also with SATA being R6 having a lot of I/O there really hits the director CPUs due to the dual parity. With only two hosts and this I/O i've seen the directors average 55-65% utilization. Hosts are using one FA on each director for a total of 8. Also the two hosts that are on here are not sharing an FA. One server is on all E0 ports and the other is on all F0 ports. Has anyone seen this SATA utilization at all in their environment and have any thoughts?
Also, what is everyones thoughts on the relocation rate? Keep it conservative at 7 or more aggressive?
Thanks
gblack2
50 Posts
0
October 12th, 2012 12:00
Just wanted to update that we reconfigured before we went production and went with R1 for the FC. Apparently not everyone agrees with it but it's what the EMC engineers are recommending with FASTVP. Likely since there is so much more data movement with FASTVP so the R1 takes those extra parity overhead off of the CPU's.
dynamox
2 Intern
2 Intern
•
20.4K Posts
0
October 12th, 2012 12:00
interesting, we have never heard that recommendation. We are doing R5 (7+1) for EFD, R5 (3+1) for FC and R6 (6+2) for SATA.
dynamox
2 Intern
2 Intern
•
20.4K Posts
0
October 12th, 2012 12:00
we are working with our SA right now, sizing a brand new VMAX as DMX4 replacement and this requirement has not come up. Maybe Quincy can share his insight ?
Quincy561
1.3K Posts
0
October 13th, 2012 07:00
I don't think there is much debate among EMC'rs these days. Everyone should be recommending R1 for the FC tier, with 300GB or smaller drives. 3+1 is prefered for the EFD tier, but 7+1 is OK. On a 40K you should always use 6+2 for SATA.
dynamox
2 Intern
2 Intern
•
20.4K Posts
0
October 13th, 2012 08:00
How am i going to justify moving from a dmx4 with r5 to a vmax with r1 ..with active data that will not sync down to r6?
Sent from my Verizon Wireless Droid
Quincy561
1.3K Posts
0
October 13th, 2012 09:00
RAID1 is the most cost effective protection for IOPs. If you want to go with a 100% FC option, then RAID5 would be fine.
dynamox
2 Intern
2 Intern
•
20.4K Posts
0
October 13th, 2012 16:00
raid 1 is the most expensive protection option, everything you guys presented at EMC world was about how only very little % of the whole box is heavy IO and you can offload that to EFDs but now you are recommending to go with the most expensive (other than EFD) protection ? If my workload is very heavy on the read side why would i go with raid 1 ?
Thanks
Quincy561
1.3K Posts
0
October 14th, 2012 08:00
If there is little writes in the workload, raid5 should be OK, but be aware of the increased chance of a dual drive failure.
For most workloads, RAID1 will provide about 2x the IOPs for the same number of disks than RAID5, hence the recommendation for RAID1 for the IOP tier.
Rajavulla
9 Posts
0
August 14th, 2013 07:00
I do not have access to this link would you kindly email me the doc to my personal email address mdraza007@gmail.com