NAS用嘅Hard Disk選擇

nchiu

其實現時NAS用什麼HD好！？以行Raid 1或 5計，用5900轉嘅節能HD如Seagate或WD嘅green系列會唔會發揮唔到NAS嘅應有效能！？

Thanks！！

lauyincheung

回復 1# nchiu

Depends on the class of NAS you use. You can check online for the throughput for both the NAS and HDD and find out where the bottleneck is. You can look on the manufacturer claims for NAS and HDD benchmarks on site like hothardware for some idea.

nchiu

回復 2# lauyincheung

Thanks for for advise, I have read the throughput of the NAS & harddisk already. but the point is, I still don't know how to estimate how the performance affected under the raid conditional. Say DS412+, the offical throughput of Raid 5 w/o Link Aggregation is around 110MB/s (large file transfer test). So under Raid 5 condition, what is the min. requirement of the sustained transfer rate of a HD to achieve 110MB/s? I really have no idea. Could you pls help & guide me how to figure it out on Internet. Thanks very much!

病態賭徒

i want 4TB... but green version is not good for raid mode?

nchiu

回復 4# 病態賭徒


my thought is... Green version won't made the NAS unstable, but will it made the Raid performance slower? if yes, what is the percentage in performance drop? coz reference to the Synology site, they use enterprise level HD to perform the test. the reason to use enterprise level HD is...  (Synology use WD2003FYYS 2TB for raid 5 test in which the benchmark of this WD is around ~110MB/s throughput in average)

(1) make the bottleneck fall back to the NAS perfomrnace itself? or...
(2) need to use enterprise level to perform such good testing result (this means the NAS perfomance faster than HD throughput)

so... what if I use a green edition to build my Raid 5 in DS412+??

lauyincheung

回復 5# nchiu

http://www.tomshardware.com/charts/hard-drives-and-ssds,3.html

There are harddisk chart for 2012 and also RAID 0 however it doesnt have on for RAID 5. According to wikipedia,The read performance of RAID 5 is almost as good as RAID 0 for the same number of disks. So maybe the RAID 0 chart is still good for some sort of comparsion. Even know it may not have the exact model you are using, but it can give you a rough estimate.

References
http://en.wikipedia.org/wiki/Standard_RAID_levels
http://www.tomshardware.com/charts/hard-drives-and-ssds,3.html

永恆的回憶

Accessing data from a RAID-5 array is as good as RAID-0, ie. theoretically multiple that on single disk, but the write performance is still slow because of generating checksum data, but it should still always reaches >100MB if you use at least an Atom CPU.

Also, apart from sequential speed, which may be trivial due to GbE limitation, seek time is also a determining factor affecting your overall RAID performance. HDDs with higher rotational speed could have a lower random seek time.

You could plan how much space you will probably fill up in your array first, before deciding which harddisk model you will buy, because when data is getting more and more, you may reach the zone over the inner circle of your harddisk, and its speed is just below the half of its maximum speed (by single disk). Disks with higher rotational speed will also more significantly benefit in such situation.

Whichever models of rotational speed you will choose, just remember to avoid WD Green (Seagate 5K4 by the way is of no problem) because its rotational speed is variable and will most probably cause the RAID to degrade unexpectedly.

nchiu

回復 7# 永恆的回憶

Thanks for your valuable info. That's why I am using seagate LP 2GB on my old 207+ instead of WD. Actually I planned to upgrade my NAS to 412+. Now I'm thinking use my old Seagate LP 2GB on 412+ and add one more LP to build a raid 5 disk array or should I upgrade all HD to 7200rpm if have more than 10% performance gain compared with LP. Any idea and suggestion on my case!?

sinister6

I have 2x WD RE4 1T in my DS209, also considering to upgrade to 412+
the question for now is to buy 2 more 1T RE4 or change to cheaper (i.e Black, Green) 2/3T HDD..  hard decision..

Livermore

回復 7# 永恆的回憶


    it seems that the WD green drives don't actually seem to vary their rotational speed (at least, the drive marked as "IntelliPower"), please read http://www.seagate.com/docs/pdf/ ... lipower_exposed.pdf