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7200 rpm vs 5400 rpm write throughputs to backup a few NAS

My customer has several NAS which runs on reasonably good
speed SATA (heard that one Hitachi SATA HDDs can give 6Gbits/sec
throughput).

There are about 20 MAC OS X that comes with Firewire 800 ports
& I intend to perform daily backup for the customers from their
MACs using Fwire 800 ports to external HDDs.

As most of the files are image files of 3-8 MBytes (each file) & there
are about 15000-20000 files, I thought of backing up to two external
HDDs per day (for daily backups) via the network (NFS from NAS)

As the 7200 rpm HDDs costs about 17-18% more than the 5400 rpms,
will need someone to share what's their experience like in terms of
IO write throughputs.  Read throughputs is not an issue as the NAS
is fast & we have a backup LAN to link aggregate two gigabit switch
ports to each of the two MAC (to get 4Gbps/sec to each MAC;  
hopefully each MAC comes with 2-3 NIC ports)

Q1:
Will there be more than 15% difference in the backup timings between
the 5400 & 7200 rpm HDDs?  One site/url even suggests that 5400rpm
HDDs can last longer than 7200rpm :
http://forums.macrumors.com/archive/index.php/t-229864.html
 Or will the extra space give rise to faster writes (by formatting with
 larger disk cluster/sector size?)
Q2:
Where will the IO bottleneck be? The Firewire 800 port speed of the
HDDs or the 5400/7000 rpm rotational latency/speed or the MAC's
Firewire 800 ports?

Looking at the following models of external HDDs:

 LaCie 7200rpm Rugged 500Gb, USB 3 + Fwire 800      PN: 301983  : US$156 + $4 shipg
http://www.amazon.com/Rugged-Triple-Firewire-Portable-301983/dp/B0058BDFXA/ref=dp_ob_title_ce

 LaCie Rugged Hard Disk Triple 1 TB USB 3.0 Firewire 800 (2x) Portable Hard Drive PN: 301984 :
http://www.amazon.com/Rugged-Triple-Firewire-Portable-301984/dp/B0058BDFZ8/ref=pd_cp_e_4
Comment
Watch Question

Commented:
I believe you can find the technical answer you are looking for in here:

http://www.zdnet.com/blog/ou/how-higher-rpm-hard-drives-rip-you-off/322

Author

Commented:

That link is dated 2006, are the comments there reliable?

Author

Commented:

& specifically I'm using those external HDDs for sustained IO in backups, not
for database nor adhoc files copying
Hi,

I would have said that you are asking a lot to get the kind of throughput you are looking for consistently across a network. It really depends on the networking kit you have.

Have you considered using time machine to a folder on the NAS for the office based machines? that would just leave you with the roaming users. Also Time machine is scheduled, and will not forget unlike most users I know.

Personally I would go with 5k4 drives, as I could get larger ones for similar money....

Regards

Gordon

Author

Commented:

In my case I'm comparing 5400rpm 1TB HDD with a 7200 500GB HDD:
how do I go about partial-stroking the 1 TB HDD so that it uses only
certain sectors/tracks (suppose the inner tracks) to get better performance?

Does MAC OS do this automatically or I simply don't fully occupy the HDD
when backing it to it?

Author

Commented:

Suppose I quarter-stroke the 1TB 5400rpm HDD, how do I build a
Truecrypt/encrypted partition or container to be on this quarter-stroked
portion of the HDD?
Gary CaseRetired
Most Valuable Expert 2013
Top Expert 2009
Commented:
A couple of notes:

=> If you quarter-stroke the drives that will help with the access time, but does NOT change the transfer rate, since the drives are still rotating at the same speed.

=>  The faster cylinders are the OUTER ones -- NOT the inner ones.     What makes them faster is the zoned sectoring, which provides more sectors/cylinder on the outer cylinders (since they have a larger circumference) ... thus the data transfer rate is faster on the outermost cylinders.

=>  Even a quarter-stroked 5400 rpm drive is unlikely to be as fast as a 7200rpm drive, since the access time is faster on the 7200 rpm units AND the transfer rate is proportionately faster

=>  The interface speed (SATA-2 vs SATA-3) is irrelevant.    Except for relatively rare buffer-PC transfers, the transfer rate is limited by the drive, NOT the interface

=>  Notwithstanding all of that, modern 5400 rpm drives (generally the "green" series drives) have excellent transfer rates due to very high areal desnities, and are almost certainly fine for what you want to do here.
Commented:
The comments from 2006 are still accurate - the same principles still hold true.

Stroking depends on how you create your partitions on the disk.  Essentially partitions are segments with the initial partition starting on one edge of the disk and the last at the other end.

By creating a partition you are effectively stroking the disk.

Refer
to Partitioning Mac OS/x
Top Expert 2014
Commented:
The article is pretty much irrelevant (and so is short-stroking) because you are talking about backup / restore which is a sequential operation, not a random access one. Assuming the disk is unfragmented and the backup-to-disk files are reasonably large then just about every seek is a single track seek. Short-stroking has no effect on single track seeks and the difference in speeds between the outer and inner tracks isn't worth thinking about since you have to read the data off a disk in the MACs that will be fragmented because it has a normal random access filesystem on it rather than sequential access data.
Excellent insights.
I've always found this entry http://en.wikipedia.org/wiki/Serial_ATA#Comparison_to_other_interfaces to be helpful BUT keep in mind the speed of the interface is not the speed of the device.  Typically hard drives max-out at about PATA 133 speed, HALF the speed of SATA II, so half of 3G is 1.5G.  So SATA II and III extra speed helps as soon as you have more than one drive attached to the bus.
USB 2.0, as well as FireWire 400/800 is slower, and thus a bottleneck.  USB 3.0 is faster (not quite as fast as eSATA) such that maximum is 7x usb2 but hard drives max out at about 3.5x usb2 or about half the speed of usb3.

RAID would be a good example of multiple drives on a bus.

Quoting the Wikipedia article: "As of April 2010 the fastest 10,000 rpm SATA mechanical hard disk drives could transfer data at maximum (not average) rates of up to 157 MB/s[8] which is beyond the capabilities of the older PATA/133 specification and also exceeds a SATA 1.5 Gbit/s link."

"Solid-state drives have already saturated SATA 3 Gbit/s with 285/275 MB/s max read/write speed and 250 MB/s sustained with the Sandforce 1200 and 1500 controller. SandForce SSD controllers released in 2011 have delivered 500 MB/s read/write rates,[12] and ten channels of fast flash can reach well over 500 MB/s with ONFI drives – a move from SATA 3 Gbit/s to SATA 6 Gbit/s allows such devices to work at their full speed. Full performance from Crucial's C300 SSD similarly require SATA 3.0"

"Standard hard disks cannot transfer data fast enough to require more than 3 Gbit/s; but they can nevertheless benefit from the later standard as reads from their built-in DRAM cache will be faster across the later interface.[13] According to Seagate "Cache-efficient desktop applications such as gaming, graphics design and digital video editing can experience immediate incremental performance using a SATA 6Gb/s interface". Drives with bigger, faster caches were introduced to benefit from the faster interface.[14]"

Now, keep in mind, the DRAM cache of the drive will help for bursts of reads or writes between ineractions delays with the user, but for BACKUP one supposes one desires a continuous sustained transfer.

Solid State Drives (SSDs) transfer considerably faster, and so with SSDs the faster bus is needed to take advantage of maximum speed.

@andyalder makes an excellent point that the speed of information coming OFF the Mac/pc being backed up may be the bottleneck, depending what drive(s) and internal interface and efficiency of the motherboard chipset and controller at xferring said data to the LAN or USB/eSATA.  eSATA has an advantage in that it is usually the same bus and controller as the SATA drives, allowing the controller to transfer drive to drive at direct high bus speeds.

Now another very important consideration.  A NAS is typically connected to an Ethernet LAN.  An Ethernet network is like a highway that is shared by ALL the cars travelling on it, the more PCs connected to the network, the higher the possibility of collisions and traffic jams.  So, if you have a fast or Gigabit Ethernet (100Mbit or 1000Mbit/s) as long as only one computer and the NAS are communicating at the time of the backup, you'll get somewhat less than that speed owing to handshaking overhead.  However if multiple computers are trying to backup at the same time, split that traffic capacity by the number of active transfers as well as additional collisions reducing throughput by a noticeable percentage.  Even switches and routers can introduce considerable bottleneck, as some inexpensive networking hubs introduce latency or strangle throughbut.  

Some external hard drive NAS devices can attach driectly via Firewire/USB/eSATA and/or Ethernet, so are you considering connecting directly from computer to NAS for each computer one-at-a-time?

eSATA and USB 3.0 would probably be faster than Gigabit Ethernet if equipped with truly fast drives.

Having said all that, you could expect the 7200rpm to be faster than the 5400rpm, certainly for internal drives and therefore by extension eSATA and USB 3 somewhat similarly.  So, assuming you haven't bottlenecked the backup scenario with a clogged LAN or slower interface, I'd look for a drive with a larger built-on cache.

Passmark has great real-world benchmarking of CPUs and hard drives http://www.harddrivebenchmark.net/   where you can see the difference between models and between SSDs vs HDDs.

Author

Commented:
excellent