Re: Pool & Logs

Thanks for information.. One more qustion why every where i can see this note for Thin Stiped Meta "Before configuring striped metadevices, please consult with an EMC performance specialist."

sauravrohilla
3 Cadmium

Re: Pool & Logs

I believe when tht document was published Online expansion of Striped tdev meta was not supported and thats the reason we were only recommending striped meta if future expansion of meta was not required.

regards,

Saurabh

rmueller2
2 Bronze

Re: Pool & Logs

Striped thin metas are supposed to perform better than concatenated thin metas.

Any idea why EMC recommends to use concatenated thin LUNs for Exchange2010?

Microsoft Exchange Server 2010: Storage Best Practices and Design Guidance for EMC Storage

(Feb 2012, Part Number h8888.4)

page 17:

What are some of the most important design considerations for Exchange Server 2010 on VMAX?

• When creating LUNs, use fewer but larger hypervolumes to improve performance.

• When using regular (thick) LUNs, use striped metavolumes.

When using thin LUNs, use concatenated metavolumes.

mmcghee1
1 Copper

Re: Pool & Logs

The recommendation in that Exchange document was not for performance reasons.  Exchange 20120 does not have high iops requirements like its predecessors so thin metas can generally give the performance needed.  Given concatenated metas are easier to expand, that's why they were recommended.  There are cases with Exchange 2010, with SRDF/S and offline checksum operations where striped can perform better, so if performance is paramount, striped should always be used. 

0 Kudos
rmueller2
2 Bronze

Re: Pool & Logs

I did a little test with Exchange 2010 Jetstress running on ESXi5 which itself runs on a Cisco B200 M2 blade. 34 x 15FC 300G drives were used for that in our VMAX-1 (5875). The .edb database drive is 100GB and I tried different stripe configurations. The key results of Jetstress are listed in the table below.

At the end I decided to go with 8 meta members. I need to create 40 of these devices, how much cache will I block with that?

I have not installed PowerPath /VE yet on the host but I will it soon.

Any other tricks to improve performance?

Meta-membersIOPSAv. Read LatencyAv. Write Latency
simple TDEV13574.958.44
214394.185.85
415183.84.33
814723.863.85
1615133.733.89
3215413.623.82
Highlighted
Quincy561
4 Tellurium

Re: Pool & Logs

Cache usage won't change.  There is no cache allocation per volume.

The only difference is the maximum WP that the meta can use.  Each volume can use up to 5% of writable cache.

0 Kudos
simmiy
1 Copper

Re: Pool & Logs

I was directed to this post from another site where my main question was: why do we still need metas if we have FAST VP. I was thinking that FAST VP would make metas the thing of the past.

0 Kudos
Quincy561
4 Tellurium

Re: Pool & Logs

simmiy

See my reply in this thread.  You may still need metas with VP or FAST VP.

0 Kudos
pmenon5
2 Iron

Re: Pool & Logs

Useful threads and thanks to all!

Thin pool created from 3+1. Do you have any best practice document for recommended RAID layout for Thin Pools?

I see many useful answers; not sure which one to click correct. clicking all helpful..................

Issue resolved resinstallation of full powerpath and HBA tuning.

0 Kudos
Quincy561
4 Tellurium

Re: Pool & Logs

When you say "RAID layout" do you mean data devices?  They should have 8 hypers per pool per disk, or the minimum number to use all the capacity of the drive.

0 Kudos