1 2 Previous Next 16 Replies Latest reply: Oct 30, 2012 2:52 AM by Christopher Imes RSS

Advice for disk config on VNX 5300

PhilippeC.

Hi folks,

 

After reading many forums, white papers et so on, I am looking for some advice on how to define disk set on the VNX 5300 we are looking for.

Actually, the overall need of the existing servers (already vmware infra which I will move to the new storage + a bundle of rack servers I have to virtualize during the next year) is the following:

 

Ratio Read / Write : 50%/50%

95e centile IOPS  :  500

99e centile IOPS : 1500

max IOPS : 2500

Max throughput: 300 Mo/s (mainly at night during backup window)

 

(I ran the I/O stats on a normal week of production)

 

The VNX will be dedicated for VMWARE shared storage,

and the VMs are W2008 (SQL server, Files server, Mail - Kerio, some sharepoint,) for prod and dev.

 

The storage would be adressed in block mode via FC (direct attachment).

 

Here is the conf of the VNX 5300 I plan to have:

 

3 x SSD 100Gb (1+1 + 1 spare) for FastCache

4 x SAS 600 Gb15k rpm for vault - used for storage ISO, model and some sources files.

9 x SAS 600 15k rpm (2 x 4+1 R5 + 1 HS) - for prod server - one lun would be in fastcache

9 x NLS 1 To 7,2 rpm (2 x 4+1 R5 + 1 HS) - 1 for dev storage / one for prod with fast cache (mail + file server)

 

To complete, we haven't yet decided or not to use snapshot (we currently are using few Veeam snapshot)

 

Q1: Am I right ?

Q2: Do I really need SAS 15k rpm, I was thinking to replace the 13 SAS 15k by 21 smaller (300 Mo) 2,5 10k disk, make it sense ?

 

  • 1. Re: Advice for disk config on VNX 5300
    hxman

    I know the recommended best practice for NL SAS drives is 6+2. So you could create a storage pool that would consist of:

    SAS RAID 5 (4+1)

    NL SAS RAID 6 (6+2)

     

    With 5.32 you can mix RAID levels in the same storage pool. Then use the FAST Cache automaticlly or assign LUNS as you wish depending on performance requirements.

  • 2. Re: Advice for disk config on VNX 5300
    PhilippeC.

    I read that Raid 6 seems useful when using 2To and above as in case of failure, reconstruction time can be very long and Raid 5 is risky.

    As I plan using 1 To disk, the main questio for me is would a 4+6 raid 6 would be faster than 4+1 raid 5 (read AND write) - but I will use fast cache, so maybe my question is useless for the write part ?

  • 3. Re: Advice for disk config on VNX 5300
    Mehdi Rezayi

    the best thing i did and it has worked well from then  is to have one storage pool with NL-SAS(6+2 , 1 spare) SAS ( 4+4 RG10 , 1 Spare ) and Enable Fast Cache for that pool . Read Cache 30 % , Write Cache 70%

  • 4. Re: Advice for disk config on VNX 5300
    PhilippeC.

    3 short questions :

    - do you use your storage for vm ? - how many do you have ?

    - do you have 15 ktpm for SAS storage ?

    - is it dedicated to prod, or is it mixed env (prod / dev-test) ?

  • 5. Re: Advice for disk config on VNX 5300
    dynamox

    max IOPS : 2500  <<-- is that host IOPs or backend iops ? If that's host IOPs i am not sure you have enough spindles to handle the workload

     

    0.5*2500 + 4 *0.5*2500 =  6250 drive IOPS (RAID 5)

     

    6250 / 180 =  35 drives ( 15k SAS)

    6250 / 150 = 45 drives (10k SAS, rounded up to 45 to go evenly in to 4+1R5 config)

  • 6. Re: Advice for disk config on VNX 5300
    PhilippeC.

    Hi

    you guess right, this is host IOPS. I know I haven't enough spindles, this why I plan to have FastCache.

     

    The max IOPs (2500) is during backup time and it is only read IOPS .

     

    So i guessed the 99percentile might the goal in IOPS : 1500

    which give me according your formula :

    0.5 * 1500 + 4 * 0.5 * 1500 = 3750

     

    3750 / 180 = 21 - 15k

    3750 / 150 = 25 - 10k

     

    17 SAS 10k + 9 NLSAS (Q2) seems better, than the 9 SAS 15k+9NLSAS.

    But I don't have a lot of margin for the future

  • 7. Re: Advice for disk config on VNX 5300
    dynamox

    i don't think you will see Fast Cache help you much with big sequential workloads like backups, you get the best bang for the buck when you are hitting the same area over and over (locality) so it gets promoted to Fast Cache. With backups you read it once and you keep on going.

  • 8. Re: Advice for disk config on VNX 5300
    PhilippeC.

    I did not expect that FastCache will be helpful for backup - already read that FastCache did not work for sequential read.

    I just hope that using FastCache will improve perf evenso the storage is not well configured (in term of number of spindles)

    Actually, I consider that backup is out of the topic for sizing the storage - I know it is the best way to do, but I have to make compromise.

    Such discussion and read in the forum, help me to decide

  • 9. Re: Advice for disk config on VNX 5300
    dynamox

    are you licensed for FAST VP ?

  • 10. Re: Advice for disk config on VNX 5300
    PhilippeC.

    the Fast VP is include in Fast Suite we plan to buy

    But as I can only get small amount of SSD drives (3), I will used them for fast cache only, I don't think it is useful to have Fast VP for SAS + NLSAS only.

  • 11. Re: Advice for disk config on VNX 5300
    dynamox

    PhilippeC. wrote:

     

    I don't think it is useful to have Fast VP for SAS + NLSAS only.

    why not ?

  • 12. Re: Advice for disk config on VNX 5300
    PhilippeC.

    OK, why not.

     

    Does Fast VP can be applied to Lun only like FastCache ?

  • 13. Re: Advice for disk config on VNX 5300
    Rainer_EMC

    FAST VP is useful for SAS and NLSAS combinations

     

    The absolute performance (IOPS/disk) and even more the per-TB performance is still quite different between these two tiers.

     

    Of course like any tiering/caching technology it work best when the working set size / locality of reference fits the size of the fastest tier.

     

    If this application is currently running on a CX4/VNX then EMC can capture I/O trace and run them through a modeling application to estimate effectiveness of both FAST Cache and FAST VP

  • 14. Re: Advice for disk config on VNX 5300
    PhilippeC.

    I though that FastVP was useful with 2 or 3 tiers with 1st tier with SSD. I never think about having 1st tier based on SAS and 2nd tiers with NL-SATA.

     

    The "application" is VM servers which are running actually on BladeCenter S (with local shared storage) and a bunch of physical servers I have to virtualize.

     

    The overall IOPS need is in the inital thread.

     

    The VM dataset can be split in two kind of VM :

    - mail / file server : 3,4 servers with 1To each serving email and file (email app is Kerio, based on flat files) - VP seems OK for this

    - SQL servers (few windows SQL servers for prod but DB is quite small) - FastCache except for the vmdk where the log are allocated.

     

    I already read some white paper but I have to extract the rigth info for me

    - I will use the block mode mainly (FC)

    - I will use the storage for VM only

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