The use of RAID 6 for pools with 1 TB or larger SATA drives is a risk mitigation recommendation. Protecting your data is EMC's first priority. This recommendation was easier to make with homogeneous pools, using Virtual Provisioning Ver. 1.0, when it was first promulgated.
The current revision of FAST Virtual Provisioning only supports a single RAID group level across all tiers. It is well-understood that using RAID 6 for all tiers may not be the most efficient use of available capacity. However, if the pool best practices are followed with regard to drive mixes, 80% or greater of the pool's total capacity will be on high-capacity SATA drives. The recommendation to use RAID 6 provides the highest level of data protection for the great majority of user data.
A user always has to take their priorities into account when considering the recommendations in Best Practices. Is their priority: availability, performance, or capacity utilization? If their priority is availability, the RAID 6 recommendation applies. If it is capacity utilization, and they believe they have sound policies and procedures for data protection in place (backups, hot spares, etc.), pursuing a RAID level 5 provisioning of FAST pools is likewise a sound decision.
When you go to create storage pools, it will want to create them in groups of 5 disks. 4+1 is the recommended config. i would not bother with the 7 disks.
If you want the best performance out of the pool from the beginning, i would add all 70 disks at the beginning. Unlike the Symm series, when you add more disks to a existing storage pool and expand, it doesnt restripe over the new disks to give you that performance gain. you just get a new chunk of space within the pool to use. And you cant specify when creating a lun were on the pool to place it.
Provisioning a pool like this is not really in-line with Virtual Provisioning's 'ease-of-use'. In addition, I suspect a large amount of labor is going to be expended to receive only a small performance advantages over allowing the wizard to provision the pool. If anything to get the distribution you're considering, you'd need a CX4-480 or CX4-960 to get two RAID groups/bus (almost).
Where there is some advantage in a manual pool provisioning, is to get a larger pool RAID group. The larger RAID group will have more inherent IOPs and a larger percentage capacity utilization than is standard though the wizard.
The maximum size of a Virtual Provisioning private RAID Group is the seven drive 6+1. The Virtual Provisioning pool algorithm can be finessed into creating this larger-than-default RAID group only one way. That is by creating pools and expanding pools with EXACTLY seven (7) drives at a time. That is, create the pool with seven drives. Then expand the pool with seven drives. This results in two private RAID groups of 6+1 each (14 drives total). All provisioning operations (creation and expansion) must be performed separately with seven drives at a time. This will result in pools containing a number of drives evenly divisible by seven (7, 14, 21, etc.).
Note this technique works with FLARE 30.5. It may stop working with a future revision of Virtual Provisioning.
In your case with FAST tiering enabled, you can go forward with 14 drives at a time (7x Fibre Channel and 7x SATA).
Thanks for your anwser, we are not using virtual provisioning on CX4-960, and is raid 5 still ok with 7 + 1 disks? So what you sugguested here is create the pool with 7FC + 7SATA and expand another lot of 14 for 6 times?
Thanks for your anwser, we are not using virtual provisioning on CX4-960, and is raid 5 still ok with 7 + 1 disks? So what you sugguested here is create the pool with 7FC + 7SATA and expand another lot of 14 for 6 times?
I would assume you are using R30 and you get virtual provisioning automatically with it..
I dont think that jsp00 was saying to do it that way. he was saying that if you do, you are making it harder then it needs to be. When you try to create a new storage pool, you can see that it asks you for the amount of disks (in SSD, FC, SATA). it tells you in that window that 5 is recommended. Now in your post that you have the 10 DAE's broken up, you are still adding 35 FC and 35 SATA. that is divisible by 5 and so is in the best practice senario. You want to add them to the pool all at the same time so taht you can benefit from your user luns being striped across all 35 disks in each tier.
If you expand a storage pool on a CX4, the additional space from the new disks become like a container inside the pool. i dont think i am wording it right but your not getting the benefit of IOPS when you expand. only addition storage space.
Since Virtual Provisioning on CLARiiON uses 41 groups you should add disks in quantities of 5. CX performance is optimal for most workloads with 41 groups. If you create a single pool using the 70 disks, you will get 14 groups of 4+1 distributed across the 10 DAEs. LUNs will write data across all of the disks so you will get pretty good balancing across the DAEs by default.
If you are using FAST and creating a pool of disks on CX4, then you are using Virtual Provisioning. Without Virtual Provisioning you can only create traditional RAID Groups and LUNs, and no FAST functionality will be available.
It sounds like you are want to put 35 x FC disks and 35 x SATA disks into a single Pool and allow FAST to tier the LUNs automatically between the two types of disks. RAID5 will support any number of disks in a single RAID Group from 3 (21) to 16 (151). Best performance from years of use in customer sites is usually around the 41 to 81 range assuming you are creating traditional LUNs and RAID groups.
With Virtual Provisioning and FAST, you are best off creating a single pool, adding the 35 FC and 35 SATA disks up front and allowing VP to allocate the disks as it sees fit. You don’t create RAID Groups manually when you use FAST, you just create the one pool and VP does the backend work for you.
If you add 8 disks to a Clariion Pool using RAID5 you will most likely get a 41 and 21 group rather than a 7+1 and the data placement will be sub-optimal. Best to create one pool, add all of the disks in at once. As Kenn2347 mentioned, any number of disks that is a multiple of 5 will be ideal for a pool so in your case 35 disks for each tier follows the best practice.
This is regarding the FAST storage pool best practice on the CLARIION CX4-960
After I read on some EMC WP on flare 30, it stated that to use RAID6 if you going to use SATA drive equal or bigger than 1 TB and above in the FASTVP, I am not sure whether this is a good design or not, so if we do ever have a double SATA drives failure, then is fully protected with R6, not sure about RAID5. Can you also point out how clariion handle double disk failure in both RAID 5 and RAID 6?
In the EMC flare 30 performance document, on page 63, it is recommending RAID 6 with SATA drives pool.
“When provisioning a pool with SATA drives with capacities of 1TB or larger, we strangely recommend RAID level 6. All other drive types can use either RAID level 5 or 1/0:
At the moment we would like to create FASTVP as R5, if we do go down the path of RAID 6, everything will have to be dividable by 8 (6+2) to get an optimal configuration, performance is bad and consumes more disk space.
At this stage, we I can think of two different RAID type configurations as below:
RAID 5 STORAGE POOL
70 Disks in the pool curve up across 10 DAEs
Select RAID 5 for manual binding, and select 7 disks of each type from 10 different DAEs,
This will create a pool of 14 (4+1) RAID groups in raid 5 configured pool. (14 x 5 = 70 drives)
FC drives
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
SATA drives
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
RAID 6 STORAGE POOL (80 disks pool)
FC disks
6+2
6+2
6+2
6+2
6+2
SATA disks
6+2
6+2
6+2
6+2
6+2
If do we decide to use RAID 5 storage pool with 1TB SATA, would you recommending us using less disks (40 disks) in a storage pool?
Any recommendation on what we should be considering using either RAID 5 or RAID 6 for storage pool with 1tb SATA drives?
I would have to seriously wonder about any organization who employs a SAN at the CX4-Level with FAST Cache that does not value availability above all else. Then again, managers will be managers. At all possible costs, as a SAN engineer being responsible (AKA your job & rear portions of your body on the line) for the data in the Storage Area Network may I suggest always designing for; in order:
Availability
Performance
Cost
Your job in this current and all future economies will thank you.
jps00
2 Intern
•
392 Posts
0
February 4th, 2011 06:00
The use of RAID 6 for pools with 1 TB or larger SATA drives is a risk mitigation recommendation. Protecting your data is EMC's first priority. This recommendation was easier to make with homogeneous pools, using Virtual Provisioning Ver. 1.0, when it was first promulgated.
The current revision of FAST Virtual Provisioning only supports a single RAID group level across all tiers. It is well-understood that using RAID 6 for all tiers may not be the most efficient use of available capacity. However, if the pool best practices are followed with regard to drive mixes, 80% or greater of the pool's total capacity will be on high-capacity SATA drives. The recommendation to use RAID 6 provides the highest level of data protection for the great majority of user data.
A user always has to take their priorities into account when considering the recommendations in Best Practices. Is their priority: availability, performance, or capacity utilization? If their priority is availability, the RAID 6 recommendation applies. If it is capacity utilization, and they believe they have sound policies and procedures for data protection in place (backups, hot spares, etc.), pursuing a RAID level 5 provisioning of FAST pools is likewise a sound decision.
kenn2347
3 Apprentice
•
542 Posts
0
February 3rd, 2011 05:00
When you go to create storage pools, it will want to create them in groups of 5 disks. 4+1 is the recommended config. i would not bother with the 7 disks.
If you want the best performance out of the pool from the beginning, i would add all 70 disks at the beginning. Unlike the Symm series, when you add more disks to a existing storage pool and expand, it doesnt restripe over the new disks to give you that performance gain. you just get a new chunk of space within the pool to use. And you cant specify when creating a lun were on the pool to place it.
jps00
2 Intern
•
392 Posts
0
February 3rd, 2011 05:00
Provisioning a pool like this is not really in-line with Virtual Provisioning's 'ease-of-use'. In addition, I suspect a large amount of labor is going to be expended to receive only a small performance advantages over allowing the wizard to provision the pool. If anything to get the distribution you're considering, you'd need a CX4-480 or CX4-960 to get two RAID groups/bus (almost).
Where there is some advantage in a manual pool provisioning, is to get a larger pool RAID group. The larger RAID group will have more inherent IOPs and a larger percentage capacity utilization than is standard though the wizard.
The maximum size of a Virtual Provisioning private RAID Group is the seven drive 6+1. The Virtual Provisioning pool algorithm can be finessed into creating this larger-than-default RAID group only one way. That is by creating pools and expanding pools with EXACTLY seven (7) drives at a time. That is, create the pool with seven drives. Then expand the pool with seven drives. This results in two private RAID groups of 6+1 each (14 drives total). All provisioning operations (creation and expansion) must be performed separately with seven drives at a time. This will result in pools containing a number of drives evenly divisible by seven (7, 14, 21, etc.).
Note this technique works with FLARE 30.5. It may stop working with a future revision of Virtual Provisioning.
In your case with FAST tiering enabled, you can go forward with 14 drives at a time (7x Fibre Channel and 7x SATA).
vTao
1 Rookie
•
19 Posts
0
February 3rd, 2011 09:00
Thanks for your anwser, we are not using virtual provisioning on CX4-960, and is raid 5 still ok with 7 + 1 disks? So what you sugguested here is create the pool with 7FC + 7SATA and expand another lot of 14 for 6 times?
vTao
1 Rookie
•
19 Posts
0
February 3rd, 2011 10:00
The configuration of our storage pool looks like this. Please correct me if this is the right step.?
Thanks,
kenn2347
3 Apprentice
•
542 Posts
0
February 3rd, 2011 11:00
I would assume you are using R30 and you get virtual provisioning automatically with it..
I dont think that jsp00 was saying to do it that way. he was saying that if you do, you are making it harder then it needs to be. When you try to create a new storage pool, you can see that it asks you for the amount of disks (in SSD, FC, SATA). it tells you in that window that 5 is recommended. Now in your post that you have the 10 DAE's broken up, you are still adding 35 FC and 35 SATA. that is divisible by 5 and so is in the best practice senario. You want to add them to the pool all at the same time so taht you can benefit from your user luns being striped across all 35 disks in each tier.
If you expand a storage pool on a CX4, the additional space from the new disks become like a container inside the pool. i dont think i am wording it right but your not getting the benefit of IOPS when you expand. only addition storage space.
Storagesavvy
474 Posts
0
February 3rd, 2011 14:00
Since Virtual Provisioning on CLARiiON uses 41 groups you should add disks in quantities of 5. CX performance is optimal for most workloads with 41 groups. If you create a single pool using the 70 disks, you will get 14 groups of 4+1 distributed across the 10 DAEs. LUNs will write data across all of the disks so you will get pretty good balancing across the DAEs by default.
Richard Anderson, EMCISA
Sr Technology Consultant, Western Division, EMC
richardj.anderson@emc.com - 206.229.9263
about.me/richardanderson
Storagesavvy
474 Posts
0
February 3rd, 2011 15:00
If you are using FAST and creating a pool of disks on CX4, then you are using Virtual Provisioning. Without Virtual Provisioning you can only create traditional RAID Groups and LUNs, and no FAST functionality will be available.
It sounds like you are want to put 35 x FC disks and 35 x SATA disks into a single Pool and allow FAST to tier the LUNs automatically between the two types of disks. RAID5 will support any number of disks in a single RAID Group from 3 (21) to 16 (151). Best performance from years of use in customer sites is usually around the 41 to 81 range assuming you are creating traditional LUNs and RAID groups.
With Virtual Provisioning and FAST, you are best off creating a single pool, adding the 35 FC and 35 SATA disks up front and allowing VP to allocate the disks as it sees fit. You don’t create RAID Groups manually when you use FAST, you just create the one pool and VP does the backend work for you.
If you add 8 disks to a Clariion Pool using RAID5 you will most likely get a 41 and 21 group rather than a 7+1 and the data placement will be sub-optimal. Best to create one pool, add all of the disks in at once. As Kenn2347 mentioned, any number of disks that is a multiple of 5 will be ideal for a pool so in your case 35 disks for each tier follows the best practice.
Richard Anderson
S_Y1
4 Posts
0
February 3rd, 2011 19:00
Cont.....
This is regarding the FAST storage pool best practice on the CLARIION CX4-960
After I read on some EMC WP on flare 30, it stated that to use RAID6 if you going to use SATA drive equal or bigger than 1 TB and above in the FASTVP, I am not sure whether this is a good design or not, so if we do ever have a double SATA drives failure, then is fully protected with R6, not sure about RAID5. Can you also point out how clariion handle double disk failure in both RAID 5 and RAID 6?
In the EMC flare 30 performance document, on page 63, it is recommending RAID 6 with SATA drives pool.
“When provisioning a pool with SATA drives with capacities of 1TB or larger, we strangely recommend RAID level 6. All other drive types can use either RAID level 5 or 1/0:
At the moment we would like to create FASTVP as R5, if we do go down the path of RAID 6, everything will have to be dividable by 8 (6+2) to get an optimal configuration, performance is bad and consumes more disk space.
At this stage, we I can think of two different RAID type configurations as below:
RAID 5 STORAGE POOL
70 Disks in the pool curve up across 10 DAEs
Select RAID 5 for manual binding, and select 7 disks of each type from 10 different DAEs,
This will create a pool of 14 (4+1) RAID groups in raid 5 configured pool. (14 x 5 = 70 drives)
FC drives
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
SATA drives
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
4+1 = 5
RAID 6 STORAGE POOL (80 disks pool)
FC disks
6+2
6+2
6+2
6+2
6+2
SATA disks
6+2
6+2
6+2
6+2
6+2
If do we decide to use RAID 5 storage pool with 1TB SATA, would you recommending us using less disks (40 disks) in a storage pool?
Any recommendation on what we should be considering using either RAID 5 or RAID 6 for storage pool with 1tb SATA drives?
tkjoffs
159 Posts
0
February 4th, 2011 06:00
I would have to seriously wonder about any organization who employs a SAN at the CX4-Level with FAST Cache that does not value availability above all else. Then again, managers will be managers. At all possible costs, as a SAN engineer being responsible (AKA your job & rear portions of your body on the line) for the data in the Storage Area Network may I suggest always designing for; in order:
Your job in this current and all future economies will thank you.
TJ