How many HDs do I need for my RAID?

A

antioch

Limp Gawd
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Jan 4, 2006
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I'm going to purchase a 4-drive NAS system to store my photos/videos/music/data. I'm going to set it up as a RAID-5 array (in an Atom based system so it should have very good read/writes in spite of needing to calculate parity data).

I've been thinking that I'll initially purchase 3x 2Gb HDDs for a total usable storage of ~3.6GB (Lose 1 HD to parity and then whatever "formatting" overhead) and expand the raid with a 4th 2Gb drive in a year or so as the need arises.

What I'd like to know is if there are any drawbacks to buying 3 HDs now and adding the 4th later as compared to buying all 4 up front? (Perhaps with 4 HDs I'll see slightly higher read performance over the 3 disk array?)

Thanks for your help.
 
antioch said:
What I'd like to know is if there are any drawbacks to buying 3 HDs now and adding the 4th later as compared to buying all 4 up front? (Perhaps with 4 HDs I'll see slightly higher read performance over the 3 disk array?)
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usually these little nas boxes are so slow that it likely won't make a bit of difference
 
115MB/s isn't slow - it's more than I get with my in-case drive (75MB/s). However, if you're referring to the difference between 3 and 4 disks then yes, I assumed it would be small.
 
I've heard lots of good things about those Samsungs that are on sale (assuming you have the latest firmware installed).
 
antioch said:
Yeah, I don't know about buying the Samsung drives. Was eying the "new" 3 platter 2Gb WD Green drives - according the Silentpcreview it's the most silent one out there right now.
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WD consumer drives in RAID is bad joojoo. No way to set TLER now. Stick to Samsung or Hitachi for raid
 
antioch said:
Yeah, I don't know about buying the Samsung drives. Was eying the "new" 3 platter 2Gb WD Green drives - according the Silentpcreview it's the most silent one out there right now.
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These drives are super quiet and cool - I just bought 4 to replace my 4 WD10EALX's and they're just as quiet and run much cooler.

I bought a 5th for a spare, we'll see how long they last - been a couple weeks now.

shabazkilla said:
WD consumer drives in RAID is bad joojoo. No way to set TLER now. Stick to Samsung or Hitachi for raid
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I've used WD drives in RAID for many years without a single issue. The key is they were all in RAID0,1 or 10. RAID5 is a no-no.
 
I've seen reports that the TLER is just paranoia.

The Samsungs consume more power and vibrate much more than the WDs do. Check it out on silentpcreview.com

Edit: Rather, the TLER issue doesn't matter for software RAID in NASes, but does in other situations.
 
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antioch said:
The Samsungs consume more power and vibrate much more than the WDs do. Check it out on silentpcreview.com
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http://www.silentpcreview.com/article1076-page5.html

Samsung EcoGreen F4 2TB

The newest EcoGreen is a huge improvement noise-wise over the disappointing F3. Measuring only 13 dBA and 15 dBA at one meter when idle and seeking, respectively, the acoustics of the 2TB F4 at last brings EcoGreen parity with Caviar Green. When it comes to power consumption, the 2TB F4 is actually superior to the 2TB Green, using almost 1W less when seeking, and it idles using the same amount of energy as the WD with its heads parked. (It should be noted however that the 2TB WD Green we are comparing it to is an older 4-platter model. Newer WD GP revisions have been shipping recently with three 667GB platters, which probably brings power down. We'll be checking on this soon.)
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http://www.silentpcreview.com/article1127-page4.html

[WD] 2 TB (3-platter) Model: This sample was the record-setter. It is our quietest WD Green sample by a hair, just about the quietest hard drive we've tested when both idle and seek noise are considered, its vibration level is extremely low, and its idle power of 2.4W almost approaches notebook drive lows. The surprise is that this sample was made in August 2010, which suggests that it may have been selling in the marketplace for many months. There may be many lucky consumers who simply bought a "2 TB WD Green", and instead of receiving one of the older 4-platter variants, got this slightly quieter newer version 3-platter drive instead.
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Yeah, the 2nd quote there about the Samsungs besting the WD 2TB is referring to the "old" 2TB drive from WD. The last quote is in reference to the new WD 2TB drives which are much better than the Samsung ones.
 
antioch said:
Yeah, the 2nd quote there about the Samsungs besting the WD 2TB is referring to the "old" 2TB drive from WD. The last quote is in reference to the new WD 2TB drives which are much better than the Samsung ones.
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I think you are overstating it by saying "much better". The noise is about the same at idle, and the Samsung actually wins with lower power usage during seek. The WD wins at idle power, seek noise, and vibration.

And judging from the newegg reviews, the Samsung is less likely to cause people problems, since the percentage of below-average reviews for the Samsung is less than half that of the WD.
 
Well you can't really rely on customer reviews of any kind as they are prone to biasing - more people will complain about failure than praise proper behavior.

I've never had a problem with WD before - but I've never used Samsungs either so I have nothing to go off of.

Does this new Samsung firmware make the drive more silent? I mean, what are the benefits to this drive? The WDs win 3/4 silence categories and have twice the cache.
 
antioch said:
Well you can't really rely on customer reviews of any kind as they are prone to biasing - more people will complain about failure than praise proper behavior.
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No, that is fuzzy thinking. It is irrelevant that people may be more likely to write a review if they have a problem when we are comparing the percentage of bad reviews between two products. There is no reason to believe that the percentage of owners writing reviews would be different between Samsung and WD drives, except perhaps if a larger percentage of people have problems with one type of drive, which is what we are interested in.

And the difference in below average reviews between the Samsung and the WD drives is not small: 11% for Samsung, 31% for WD (in past 6 months, 12% for Samsung, 31% for WD) . It is a good bet that the difference is meaningful, and that people are less likely to have problems with the Samsung drives, and more likely to have problems with the WD drives.
 
Sure. But you still haven't answered my question as to why the Samsungs are better? If I get a dead WD drive I can have it replaced from the store or WD and it will perform better than the Samsung. If I dont get a DoA WD drive then I'm in even better shape.

Like I said, I have a 1.5TB WD Green which had bad newegg reviews and I have had no problem with it in the ~2 years I've had it.
 
antioch said:
Sure. But you still haven't answered my question as to why the Samsungs are better?
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Yes I did -- the Samsung drives are much less likely to cause problems for their owners. Maybe you don't care about wasting time messing around with your computer when something goes wrong, but many people do.
 
Brahmzy said:
These drives are super quiet and cool - I just bought 4 to replace my 4 WD10EALX's and they're just as quiet and run much cooler.

I bought a 5th for a spare, we'll see how long they last - been a couple weeks now.



I've used WD drives in RAID for many years without a single issue. The key is they were all in RAID0,1 or 10. RAID5 is a no-no.
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Why do you say RAID 5 is a no-no?
 
starting with 3 drive RAID5 array should be fine but building an array with all bays fully loaded would be better.

depending on the system (cpu, controller, hd size), building the array can take btw 10 to 24hrs to complete. now if you build array with 4 disks and there is a problem (power outage, bad disk), you can just start again as no data is at risk.
if you try expanding the array later (enlarging array from 3 to 4 disks) and there is an issue (again, power outage, bad disk), there is a risk to data already on array.

large hds are fairly cheap now so might as well load up all the bays now.

regarding disks to use, if you want WD or seagate, stay clear of the green/5xxx rpm drives, they are not designed for RAID arrays.
the best cheap green drives to use are the samsung or hitachi 5k3000 series drives. they are considered to be the best (safest) option as they haven't had the RAID'able features striped from the drives.

as tgrimley has mentioned, your nas isn't going to be super fast but i wouldn't consider it slow either. at best you are going to be limited by the NIC's Gigabit interface (max theretical of 125MB's but closer to 80-100MB's). more likely you'll be limited by the system (cpu, RAID controller etc).

i've got 2 old 'thecus n5200's' RAID5 NAS's. my newer 'n5200pro' (modded: celeron M 1.6GHz to pentium M 2.0Ghz + 1Gb RAM) has 3 hitachi 5k3000 2TB disks in RAID5. i get between 40 to 80MB's read/writes.
 
Now I find out about this. I have a Sans Digital RaidTower in RAID 5 with 5 2TB hard drives.
I have a mix of Samsung, Hitachi and WD. I guess it might be risky.
Anyway I'm out of space so I'm going to build another one anyway. I think I will stick with all Samsung drives this time.
Thanks for the info.
 
aphasia said:
Regarding disks to use, if you want WD or seagate, stay clear of the green/5xxx rpm drives, they are not designed for RAID arrays.
the best cheap green drives to use are the samsung or hitachi 5k3000 series drives. they are considered to be the best (safest) option as they haven't had the RAID'able features striped from the drives.
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That's an interesting point. I hadn't considered Hitachi drives. The last Hitachi I bought was several years ago - one of the first 7200RPM 100GB 2.5" drives. I'll look into the 5k3000 - but my primary concern is noise and heat.

You said that the 5k3000s still have RAID features intact (as opposed to stripped WD drives). Which features are you referring to?

Is there a Hitachi HD toolbox available? Something that I can use to adjust AAM and TLER on the drives?

Thanks!
 
antioch said:
That's an interesting point. I hadn't considered Hitachi drives. The last Hitachi I bought was several years ago - one of the first 7200RPM 100GB 2.5" drives. I'll look into the 5k3000 - but my primary concern is noise and heat.

You said that the 5k3000s still have RAID features intact (as opposed to stripped WD drives). Which features are you referring to?

Is there a Hitachi HD toolbox available? Something that I can use to adjust AAM and TLER on the drives?

Thanks!
Click to expand...

the features i was referring to specifically (regarding RAID)

1. drive(s) do not spin down
2. drive(s) do not park heads
3. drive(s) use 512k blocks (at least for the 2TB drives, think the 3TB use 4K)

with head parking, i know the WD green drives used (still do i think?) contact stop on the physical platter. a big no-no for me.

with acoustic management, hitachi Feature Tool (prior to v2.13) did have the option but has since been removed (original from major geeks forum)
http://forums.majorgeeks.com/showthread.php?t=234339
the current hitachi Feature tool is version 2.15.

now whether its needed any more is debatable. when i bought mine 5k3000's my orginal post here;
http://hardforum.com/showthread.php?t=1587598
and i was doing my drive tests on all 3 drives (benching, surface test with DFT), i couldn't hear the drives at all. i was testing the 3 in a open case on an old intel MB with ICH7 chipset. frankly i couldn't hear anything thing other than the WD raptor HD (boot) and the CPU fan.

now finally onto the TLER (or hitachi's version CCTL). there was a lengthy discussion, 3 pages worth, on the topic (across all 4 manufacturers - WD, Seagate, Samsung, Hitachi). the consensus it CCTL cannot be enabled, at least publically. however a lot of forum members use these drives (7Kxxxx, 5Kxxxx) and haven't had a drive dropped or if they did it was b/c the drives was going bad and needed replacement period.
also CCTL is really only an issue with hardware RAID controllers not software. it seems that the hitachi drives generally behave themselves in arrays.

the various hitachi tools;
Drive Fitness Test v4.16
Feature Tool v2.15
OGT Diagnostic Tool
http://www.hitachigst.com/support/downloads/

there're a couple others tools but they're not relevant to RAID (advanced format alignment util etc).
 
i just remembered you (antioch) asked about noise and temps.

i covered noise on the 5k3000's in my last post but it's a subjective reply. all of the 5xxx rpm drives are going to be quieter than then 7200rpm HDs. the difference btw them isn't great.

temp wise, at least for my 5k3000's in it's current enclosure (single 120mm exhaust fan at back, no fan over HD's), i'm getting 27C across all drives. this was after transferring several GB's of data. the ambient temp in the room is fairly cool tho, around 16C.
 
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