Author Topic: Hard Drive recommendation for Transparent RAID users  (Read 6102 times)

Offline Brahim

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Hard Drive recommendation for Transparent RAID users
« on: December 04, 2013, 02:59:52 pm »
For users running Transparent RAID and looking to buy new hardware, an often reoccurring question is which drive to buy.

Transparent RAID favors disk with low access time - especially for the PPU disks.

As such, it is a good idea to consult the following resources:

Here are some sample charts comparing the WD 4TB Black drive against some other drives.
Note how the RED drives don't fair too well in these benchmarks.



« Last Edit: December 04, 2013, 03:04:56 pm by Brahim »

Offline shaun.arundell

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #1 on: December 04, 2013, 04:13:45 pm »
Brahim

I have a load of WD  3TB Reds, IS it worth will replacing the WD Red PPU(s) with disks with better access times (segate etc) ?.
Will that make a substained difference on writes or will the WD red  DRU wirte times dominate ?

shaun
 

Offline Brahim

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #2 on: December 04, 2013, 04:37:36 pm »
If buying new disks, yes, it is worth going with faster disks (lower access time) for PPU.
So, for your next disk upgrade, buy faster disks and make them PPUs and move the RED disks to DRU duty.

It is best to wait and see how the new performance mode fairs out though.
It does improve the performance of disks with high access time in sequential operations.
So, unless you have a heavy concurrent workload, this might be good enough.

The difference between disks with low access time vs high access time is significant.
I have setups that reach performance up to 65% of source disk sustained write speed in TCQ and energy efficiency mode. Compare that to other users only getting as low as 25% for the same settings.
It is all about access time and in particular when in energy efficiency mode.

Offline SentinelBorg

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #3 on: December 05, 2013, 07:54:32 am »
The Western Digital SE 4TB should be a good choice for parity disks. Their performance is somewhat in between RE and RED on the level of the Black, but they are much cheaper than the RE and are allowed for continuous operation in storage systems unlike the Black.

Offline Brahim

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #4 on: December 05, 2013, 09:36:00 am »
The Western Digital SE 4TB should be a good choice for parity disks. Their performance is somewhat in between RE and RED on the level of the Black, but they are much cheaper than the RE and are allowed for continuous operation in storage systems unlike the Black.

Looking at the ATTO write benchmarks below (taken from here), you are correct that the SE are a good compromise.
The Seagate Barracuda is a better choice though.

Offline dscline

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #5 on: December 05, 2013, 09:53:59 am »
The Western Digital SE 4TB should be a good choice for parity disks. ... and are allowed for continuous operation in storage systems unlike the Black.

Though wouldn't a parity disk only be active during writes and RAID tasks like verify?  I wouldn't think they would normally be operating more than, or even as much as, a typical desktop OS drive, so the 24x7 blessing wouldn't seem that critical.  I would be more inclined to use a 7200 rpm drive such as the Black for parity, despite not being targeted for server or NAS use.
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Offline terrastrife

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #6 on: December 05, 2013, 10:26:50 am »
I would still buy the Black over an Se, currently the Se is based on the original Black design, the Black has been updated and is faster, not to mention much cheaper.

Offline Brahim

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #7 on: December 05, 2013, 11:11:39 am »
@dscline
Great point. If one's array is not write heavy, then the PPUs will experience lot of idle time.
The PPUs still need to be fast for when they are needed.

@terrastrife
Yep, price/performance wise, the WD Black wins.
The argument for the SE would supposedly be reliability. This, however, needs to be backed by numbers.
We all know that reliability can sometimes be a case of "luck of the draw".

Offline dscline

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #8 on: December 05, 2013, 12:24:45 pm »
the Se is based on the original Black design
Yeah, my bad, I had it in my head that the SE was a 5400 RPM drive. Which is silly, as there wouldn't be much to differentiate it from the Red.  Though from what I remember when I was looking at them, their error rates & load cycles weren't any better than the consumer drives, so I didn't really see the point in paying a premium for them.
WHS 2011
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Supermicro C2SEA, Q9505s (stock), 4GB
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Offline shaun.arundell

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #9 on: December 05, 2013, 09:01:22 pm »
I just brought a few WD 3TB Blacks today and will post some  TRAID disk benchmarks tonight and I hope to run a couple of copy  scenario's over the weekend

1. 1 Black PPU + 1 Black DRU
2. 2 Black PPU + 1 Black DRU
3. 1 Black PPU + 1 RED DRU
4. 2 Black PPU  + 1 RED DRU
5. 1 RED PPU + 1 Blakc DRU <= proably wont bother

Each scenario will have a 20hr raid parity construction phase so It's going to take some time

shaun

Offline terrastrife

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #10 on: December 05, 2013, 09:30:35 pm »
Each scenario will have a 20hr raid parity construction phase so It's going to take some time
Urm, you may have controller bottlenecks if it's taking 20 hours. My Verify Sync takes 12 hours offline and 15 hours online.

Offline shaun.arundell

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #11 on: December 05, 2013, 09:55:30 pm »
forgive me for to exaggerating. Those times would be about right for me too.

shaun

Offline Brahim

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #12 on: December 06, 2013, 12:54:42 am »
...
Each scenario will have a 20hr raid parity construction phase so It's going to take some time

shaun
Why bother computing parity if this is just for testing?
Just initialize by doing nothing. The parity might not be correct, but that won't affect the tests.

Offline shaun.arundell

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #13 on: December 06, 2013, 03:51:17 am »
Ah Ah - that will say a lot of time

Offline IVB

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Re: Hard Drive recommendation for Transparent RAID users
« Reply #14 on: December 11, 2013, 08:46:20 pm »
FYI for the avnation.tv guys, this is Vivek (dude from tonights podcast), this is what I referred to on the 12/11 episode. The product I use is tRAID, aka Transparent RAID, one of the product offerings.

(Sorry Brahim, wanted to provide some written context so people coming here without checking my Google+ page would know what I was talking about)