Multiple hard drives in external enclosure

[Edward Diener]

I am buying an external enclosure in which I can install up to 4 sata
drives and which connects to my computer via an eSata interface. I will
be using these drives mainly for backup purposes.

Does it matter if all the drives I buy are different models or should I
try to buy all drives of the same model ?

The drives will all be eSata 3.0 GB drives, since that is the maximum
speed my mobo supports. I have been looking at a number of models: hard
drives from Western Digital, Seagate, Hitachi, Toshioba, and Samsung,
all listed on NewEgg. I am debating whether I should buy different
drives or all one or maybe two different models. I am guessing that
either way should not make a difference, but I wanted to ask here first
among those who know hard drive technology better than I do.

 

[Edward Diener]

I use such a box. I run the box from a PCIe card and the
four drives are JBOD--so each one runs independently and has
its own drive letter (FGHI). Could run RAID options, but
decided it was safer/smarter to run indendently. Once the
new 4TB HDDs become reasonable in price, I will replace the
1TB drives in the box one at a time. I have four Seagate
5900 RPM drives in there and have had zero failures running
them for nearly four years. I will move the 1TB drives to
individual USB2 or USB3 boxes to use as multiple backups for
essential info on the C-drive. My existing USB2 box is PATA
only and limited to 750GB maximum capacity (it has a 120GB
HDD in it now), so the need to upgrade more than that drive
is real. The Thailand floods drove up prices and limited HDD
production capacity for some time, so it will be a bit more
time until things get back to normal again. This summer it
might get interesting, but we will know for sure by next
Sept-Nov (students back to college, Black Friday, etc).

So you have all 4 of your drives the same. Do you see that as an
advantage over having 4 different drive models ?

 

[Rod Speed]

Edward Diener wrote

Gerald Abrahamson wrote

So you have all 4 of your drives the same.

There is no need to do that with a JBOD config and he said
that he plans to upgrade them one at a time, so will have a
mixed config at least until he has finished doing that.

It'll work fine in a JBOD config.

Do you see that as an advantage over having 4 different drive models ?

There can be some downsides with such a dramatic
differenc in drive size with some RAID configs.

But not with a config where its just manufacturer thats
different and not the speed or size of the drive by much.

Gets more tricky with a RAID config and dramatic
differences in RPM etc, but not with JBOD.

The main advantage with a mixed config and JBOD is that if one
of the drive models is notorious for a real design problem, you arent
likely to lose all your backups etc.

 

[Arno]

From a redundancy POV, you want different drives in different
enclosures because 1) a drive model could have a systematic
problem and 2) the enclosure could blow up (falls over, PSU
fries the drives, ...)

Common sysadmin wisdom is that you need at the very least 3
independent rotationg backup media sets (here: drives) for the
backup to be reliable. Here you have one.

Arno

I am buying an external enclosure in which I can install up to 4 sata
drives and which connects to my computer via an eSata interface. I will
be using these drives mainly for backup purposes.

 

[Yousuf Khan]

I am buying an external enclosure in which I can install up to 4 sata
drives and which connects to my computer via an eSata interface. I will
be using these drives mainly for backup purposes.

Does it matter if all the drives I buy are different models or should I
try to buy all drives of the same model ?

The drives will all be eSata 3.0 GB drives, since that is the maximum
speed my mobo supports. I have been looking at a number of models: hard
drives from Western Digital, Seagate, Hitachi, Toshioba, and Samsung,
all listed on NewEgg. I am debating whether I should buy different
drives or all one or maybe two different models. I am guessing that
either way should not make a difference, but I wanted to ask here first
among those who know hard drive technology better than I do.

One problem I see is that if you want to use software RAID on it, such
the RAID built into Microsoft's Windows Disk Management, then it may not
allow such thing over an external enclosure. I know I ran into this
problem when when I was using an external USB enclosure.

Yousuf Khan

 

[Edward Diener]

One problem I see is that if you want to use software RAID on it, such
the RAID built into Microsoft's Windows Disk Management, then it may not
allow such thing over an external enclosure. I know I ran into this
problem when when I was using an external USB enclosure.

Since it is an external enclosure I do not intend to use RAID, but just
have the drives for various backup purposes. That may go against the
people who comforatbly use RAID with internal drives, as a redundancy
measure, but I have always found it "good enough" to periodically backup
data to external partitions. One of these days I may switch to RAID for
redundancy but I am afraid I am not there yet,

 

[Edward Diener]

From a redundancy POV, you want different drives in different
enclosures because 1) a drive model could have a systematic
problem and 2) the enclosure could blow up (falls over, PSU
fries the drives, ...)

Thanks. Having different modules is then a pretty good idea. At the very
least I can get a better idea of which models/manufacturers are more
dependable than others over the long run.

Common sysadmin wisdom is that you need at the very least 3
independent rotationg backup media sets (here: drives) for the
backup to be reliable. Here you have one.

I will probably backup to more than one drive or do periodic backups
which go to different drives. Backing up to 3 drives at one time deos
seem like overkill to me, even if it is considered tecnically safest.

 

[Edward Diener]

Edward Diener wrote


There is no need to do that with a JBOD config and he said
that he plans to upgrade them one at a time, so will have a
mixed config at least until he has finished doing that.

It'll work fine in a JBOD config.


There can be some downsides with such a dramatic
differenc in drive size with some RAID configs.

But not with a config where its just manufacturer thats
different and not the speed or size of the drive by much.

Gets more tricky with a RAID config and dramatic
differences in RPM etc, but not with JBOD.

The main advantage with a mixed config and JBOD is that if one
of the drive models is notorious for a real design problem, you arent
likely to lose all your backups etc.

Thanks ! That's a good reason to go with diffent models. All the drives
will probably be the same size initially but as I upgrade in the future
I will choose larger sizes as appropriate. I do intend just to use JBOD.
RAID still seems to me to be problematical, but tmaybe that is just my
own old-fashioned approach. Also with an exteranl enclosure it seems to
me that RAID would be just to slow ( as opposed to an array of internal
drives ).

 

[Edward Diener]

It depends on your usage. I deliberately have the same
drives because they were expected to be reliable (5900 rpm)
and I did expect to eventually move them out to other
devices (USB boxes or similar) as they got replaced. It also
meant I could back up data from the C drive to one of them
AND to the existing 120GB USB drive (so have 3 copies of
data). I could use one as a C drive in a new system build
when I buy a new 4TB to put into the eSATA box.

I use one of the four 1TB drives in the eSATA box to record
OTA TV and it works fine for that purpose. One drive is for
backup storage for the other drives (selected stuff, not
everything). The other two hold assorted "stuff" that is
needed for one thing or another--you know how it goes.

My general requirement for a replacement drive is for the
next drive to be AT LEAST 4x the capacity of the drive it is
replacing. So, the capacity is finally being reached. If
larger sizes become available, I would consider them in lieu
of the 4TB HDDs. The Seagate 4TB are 7200 rpm, so I am less
interested in them--would prefer 5900 rpm. I am looking for
capacity and reliability, not super speed. SATAII drives
have a continuous data-transfer rate that is not
super-fast--mine are rated about 125-150MB/sec. So, a RAID
can about double that--but then you hit the bus transfer
capacity limit. So, you need a different method of
connection in order to truly handle high transfer speeds a
RAID can deliver (fiber optic?). I don't need that (yet!).

Thanks for the info. I am also looking for reliability and gather that
5900 RPM drives are generally more, or at least as, reliable than the
faster 7200 RPM. I also initially was looking for the 7200 RPM speed,
1TB drives, but then decided that 5900 RPM would be quite adequate and I
could get them for a good price even at 2 TBs.

I ended up choosing a SAMSUNG EcoGreen F4 HD204UI and a Western Digital
Caviar Green WD20EARS. I will buy two more drives for my 4-drive
external enclosure eventually.

 

[Edward Diener]

I use a real simple system that is easy to remember.

My data currently sits on C--and I created a single
directory with most of my data and files stored. There are
1-2 other programs/files I also back up, but easily done.

I decide which drive in the SATA box is to be the first
backup. Then I create a new top-level directory on othat
drive with easy to remember name AND a date (Backup 2012-03,
for example). That way, it automatically sorts files by date
as long as I use the same file name with the appropriate
date. You copy your data to that new file--and you can make
subdirectories for other files/data if needed.

I am actually used to backing up entire partitions, just in case of
serious hardware failures. But I do understand just backing up key data
files.

Once done, making a second backup is easy. I just "send"
that backup file to the USB drive--and walk away to do other
stuff while it is copying. That gives you three copies--one
of which is removable (the USB box). I keep by my USB box
powered OFF most of the time just to make sure I can NOT
write to it "by accident". I turn it ON to make a backup and
then disconnect it and power it off when the backup is done.

Then you are backing up the data twice. You have your original files and
two backups. That sounds reasonable to me. I thought you originally were
suggesting 3 backups of the original data, and that seemed overkill.

I would recommend USB3 if you do not have a good USB2 box.

My mobo does not come with an internal USB3 port, only a number of USB2
connections and more USB2 ports off of those connections than I need. I
would have to purchase a card with USB3 support. Then I would have to
get a separate external drive enclosure which would support USB3
transfer. Recommendations for either are appreciated.