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Rukah

Lets talk HW RAID5, ESXI and slow data xfer speeds.

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Rukah

I have spoken to a few people by PM and after reading through some of the posts, it seems like a common issue.

 

I am thinking of getting a N40L, HP P410 RAID5 Card and Running ESXi (Server08R2/CentOS) - Many people are saying they are getting terrible read/write performance on their HW raid arrays when running ESXi - Can anyone verify how much slower and what the cause/resolution may be?

 

I am keen to get a Microserver, but will probably give it a miss if this issue is widespread.

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cbridge

Rukah,

 

Yes, I have this problem. Although on a simple N54L (non Raid) setup. 

 

In fact, I posted on the rather excellent tinkertry.com whom suggested I try over here.. then I saw your tantalizing topic heading.

 

Sadly, I don't have anything to help, other than the detailed explanation that Lavpannekake gave, and the link he gave; see the comments at the bottom of this post http://www.tinkertry.com/tp-link-gigabit-pci-express-network-adapter-tg-3468-for-esxi-5-5-home-lab/ which leads to more on the topic here, http://forums.freenas.org/threads/sync-writes-or-why-is-my-esxi-nfs-so-slow-and-why-is-iscsi-faster.12506/.

 

More here: http://wahlnetwork.com/2011/07/20/solving-slow-write-speeds-when-using-local-storage-on-a-vsphere-host/

Edited by cbridge

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FiLiNuX

Cbridge,

 

I think you & Rukah might be talking about two separate things here.  I am GUESSING you are having/had problems with slow data transfer speeds in regards to your network while I believe Rukah is inquiring about read/write speeds of HW raid arrays in the ESXi environment.  If I am incorrect then I apologize but if not I would suggest starting a new thread if your still having issues with the network xfer speeds in ESXi as LOTS of folks on here could probably help. 

 

Rukah, 

 

I am a HUGE fan of the N40L and have heard specific instances of some issues but nothing across the board super widespread that I know of with the RAID slowdowns.  Also one of the well known members on here has just posted about the prices of the HP RAID cards prices coming down that you might find interesting if you are looking to get one.  Is the N40L you are looking into a new or used unit?  I only ask as it seems most who are looking into buying a micro server as of late always look at the N54L or a Gen 8.  

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Rukah

Also one of the well known members on here has just posted about the prices of the HP RAID cards prices coming down that you might find interesting if you are looking to get one.  Is the N40L you are looking into a new or used unit?  I only ask as it seems most who are looking into buying a micro server as of late always look at the N54L or a Gen 8.  

 

I am looking at a N54L (New) - Are you able to link the post about the RAID card prices coming down? (I am looking at a P410)...

 

At first I was set on running ESXi and then Server 2008 R2 ontop of that... But as of late I am thinking the box will be a bit underpowered :/

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DanielN

I haven't had any problems I picked up a P410 and 1GB Flash Backed Write Cache (FBWC) for $250 and I'm running two RAID5 volumes... 1 set with 1TB drives, the other set with 2TB drives.

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schoondoggy

I am looking at a N54L (New) - Are you able to link the post about the RAID card prices coming down? (I am looking at a P410)...

 

At first I was set on running ESXi and then Server 2008 R2 ontop of that... But as of late I am thinking the box will be a bit underpowered :/

Here is my original post;

http://homeservershow.com/forums/index.php?/topic/6367-hp-smart-array-market/

I would consider buying this;

http://www.ebay.com/itm/HP-462919-001-Smart-Array-P410-0MB-SAS-PCIe-x8-RAID-Low-Profile-SFF-462860-B21-/281130507901?pt=US_Server_Disk_Controllers_RAID_Cards&hash=item4174af1e7d

and this;

http://www.ebay.com/itm/HP-462967-b21-512MB-BBWC-KIT-FOR-P410-P411-P212-PROLIANT-DL360-G6-DL380-G6-/111189875552?pt=US_Server_Disk_Controllers_RAID_Cards&hash=item19e36edb60

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Rukah

 

Great info - Thanks... I saw a post by LoneWolf...

 

 

I am currently using a P410 in my Microserver; as others have said, you do indeed need the low-profile bracket for the card to fit properly, at least if you wish to firmly anchor it in (you could technically remove a full-height bracket and use the card).

 

You definitely want a cache module; if you haven't bought one, I'd be happy to send you a 256MB one for the price of shipping, as I have two lying around. 512MB and 1GB ones are also available. There are four types of cache modules:

 

256MB (with optional battery backup)

512MB (optional battery backup)

512MB (flash-backed)

1GB (flash-backed)

 

A battery backup module or (in the case of the flash-backed models) capacitor module is necessary if you wish to safely use write-back cache, although you can override the default write-through cache without a battery (not recommended unless you have a UPS at the very minimum, as this risks file corruption in the event of a power failure). The flash-backed modules have the advantage that there is no battery to wear out over time; the capacitor module (which looks much like the battery module) only needs enough energy for the cache module to write changes to flash. Also, a battery module will lose charge if a system remains powered down too long after power failure; the flash-backed write cache can hold data indefinitely.

 

The 256MB cache is 40 bits wide in its memory path; the 512MB and 1GB modules are 72 bit, so for heavy or sustained I/O, the larger cache modules are higher performance. Also, a cache module (of any size) is required for RAID-5.

 

HP has excellent driver and firmware support for the P410 controller; make sure you update the firmware on your card to the latest prior to using it. Also, I recommend downloading HP's .ISO of their Offline Array Configuration Utility (ACU) for configuring your logical drives after the BIOS update and prior to setting up your operating system. If you have further questions, let me know.

 

So to clarify, I need to make sure I purchase:

  • A low Profile RAID Card
  • 512Mb Memory Module
  • Should I get a battery backup module or a capacitator module? (Keep in mind I don't have a UPS - and do experience occasional power outages) - LoneWolf says "The flash-backed modules have the advantage that there is no battery to wear out over time".... This sounds appealing to me... is the "flash-backed module" the same as a battery module? i.e I am confused :s

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timekills

 

Great info - Thanks... I saw a post by LoneWolf...

 

 

So to clarify, I need to make sure I purchase:

  • A low Profile RAID Card
  • 512Mb Memory Module
  • Should I get a battery backup module or a capacitator module? (Keep in mind I don't have a UPS - and do experience occasional power outages) - LoneWolf says "The flash-backed modules have the advantage that there is no battery to wear out over time".... This sounds appealing to me... is the "flash-backed module" the same as a battery module? i.e I am confused :s

 

 

You should DEFINITELY get an UPS. The battery backup is a great addition, but for reasons beyond just RAID corruption you should have an UPS, even if you never suffered through "occasional power outages." 

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schoondoggy

 

Great info - Thanks... I saw a post by LoneWolf...

 

 

So to clarify, I need to make sure I purchase:

  • A low Profile RAID Card
  • 512Mb Memory Module
  • Should I get a battery backup module or a capacitator module? (Keep in mind I don't have a UPS - and do experience occasional power outages) - LoneWolf says "The flash-backed modules have the advantage that there is no battery to wear out over time".... This sounds appealing to me... is the "flash-backed module" the same as a battery module? i.e I am confused :s

 

Yes you need a LP card.

I prefer 512, but 256 will work.

They are to different modules. The flash based model uses the capacitor. The ram based one uses the battery. The flash is nicer, but it is very expensive. Page 13 has the part numbers for the individual cache modules;

http://h18004.www1.hp.com/products/quickspecs/13201_div/13201_div.pdf

As stated above you need a good ups.

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