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| Three Tier AO and Best Practice https://3parug.com/viewtopic.php?f=18&t=2805 |
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| Author: | ajgwilson [ Wed Feb 21, 2018 7:43 am ] |
| Post subject: | Three Tier AO and Best Practice |
I am looking for some advice from experienced admins. (Sorry for terminology errors but I am new to 3PARs.) We have a new 3PAR managed by a 3rd party. It has the following disks installed: 16 x 1.92TB SSD 24 x 600GB SAS 15k RPM 32 x 1.8TB SAS 10k RPM These have been configured as three CPGs (all RAID5 (5+1)) and then used to create a three tier AO. My rough estimate is that the 15k CPG contributes around 10% of the capacity whilst being configured as Tier 1. Whilst migrating VMs to this 3PAR storage, we experienced a major performance issue when the 10k CPG (Tier 2) disks became overloaded (IOPs). This happened at the same point as the Tier 1 was quite full and backups were taking place (which use 3PAR snaps). First question: Is it sensible to have an AO configured in this way, and if not why not? Second question: I have suggested moving to using a two tier AO consisting only of the spinning disks with Tier 1 being the 10k disks (and Tier 0 15k disks). Using the SSD for a dedicated flash CPG so we can take advantage of dedup (we are licenced for compression and dedup). Possibly with some SSD being allocated for flash cache. We have a good understanding of what data will benefit from faster storage and we expect that this same data would dedup well. Is this a sensible approach to adopt? NB We cannot now change the hardware which we now own. Also very happy for any other advice. I am working my way through best practice information but my lack of hands on experience means I am unsure how best to direct the third party. Thanks in advance. |
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| Author: | MammaGutt [ Wed Feb 21, 2018 7:46 pm ] |
| Post subject: | Re: Three Tier AO and Best Practice |
From the description the config doesn't sound that bad. The only thing I notice is that you have very little spinning media per CPG. If I were to start from scratch I would have only one FC CPG with more drives to get more performance. If you get performance issue at T2 during migration, it sounds like there is a config issue. T1 should be base CPG and this is where you should get issues at migration if you get any. Ao without SSD at all sounds like a bad call, but you could limit it to a few TB if you want to use some SSD for dedupe/compression. For DECO I would suggest that you ensure you have a 3PAR model optimized for flash (8440..or any xx40) but I have a feeling that you're stuck with a 8200 based on the SSD/HDD combo. |
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| Author: | cali [ Thu Feb 22, 2018 11:08 am ] |
| Post subject: | Re: Three Tier AO and Best Practice |
First I would change all to R6. (2x R5 4+1 have same Parity as 1x R6 8+2, but R6 have much better resistance) Split the SSD in two CPG. One for SSD only Applications (with Dedup) and one for AO T0. Configure AO for Performance. Set FC AO T1 to use Maximum Space. |
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