Hitachi
Unified Storage Specification and Features
Few days back I attended the Hitachi HUS modular training,
and while the training was going on, as I have already worked on NetApp storage,
so I was keep on comparing Hitachi each feature with the NetApp unified storage
features, but apart from the architecture (hardware & CPU and cache) I have
not found anything new in Hitachi unified storage. While one thing I can say
that installing the Hitachi storage and upgrading the Hitachi firmware’s are
quite easier than the NetApp storage and even managing is also quite easier
than the NetApp GUI.
Hitachi unified storage is not unified in Hardware
, but it is unified from software front, means they have Hitachi Command
suite for management of Hitachi SAN/NAS
and even the other VSP, ASM, others product.
When I asked that why they have not merged all the
hardware in single hardware like NetApp, their straight answer was they don’t
want to compromise on performance, more hardware means good performance,
because each hardware have its own memory, ram, CPU to perform its own task,
while merging in single hardware the load on central CPU will increase and then
there will be more hardware failure, decrease in performance.
Well I have not used any Hitachi product so I
cannot say that whether they are good or not in performance but the examples of
some of their customer feedback they
presented in training, that quite say that Hitachi is really good performance
storage box. If you see their controller architecture their you can see that
there is 6GB/s connectivity between the its RAID Processor (DCTL) chip or we
can say that the between the two controller there is 6GB/s connectivity which help their controller to
do the load balancing, that’s good, because this was new to me, because I have
not seen this in NetApp, yes controller failover and failback happens in NetApp
, but NetApp never say that their failover /failback link do any type of load
balancing activity.
Yes I know that in NetApp the disk are owned by
the respective controller and their load will be handled by that owned
controller only, and each controller have some load handling capacity, but lot
of customer don’t understand that and they keep on adding the disk shelf to one
of the controller in the hope that in future they will add to the other
controller and by this one of the controller which have more number of disk
owned by the others have to handle lot
more iops than other and hence the utilization of that controller
increases and the performance get decreases.
As I have also worked in some of the EMC VNX
series storage box, which are unified storage box of EMC, well there they
strictly recommend to keep adding the expansion shelf alternatively, for ex if
one expansion shelf is attached to the one of the controller bus then other
expansion shelf should be attached to the other controller bus, for load
balancing.
So that Cleary state that neither the NetApp nor
the EMC have such type of 6GB/s internal connectivity between the controller
which can do the automatic load balancing like Hitachi, but still I cannot
write much because I do not have any
experience in Hitachi automatic load balancing features so could not say that
whether it really works fine .
But by doing some of enquiry with some of the
colleagues there who have good experience in Hitachi storage stated that they
never seen much of hardware failure in Hitachi except the disk, I mean like
controller failure, PCI card failure, or fan failure or power supply failure
types. But I can say the hardware failure in NetApp is quite higher than the
other vendor storage product. That’s my personal experience and I don’t know
why, even you can experience that suddenly some mail will get dropped in your
inbox from NetApp stating that please do this or that firmware upgrade urgent
to save you controller getting failed (W.T.F) and then you have to plan for
that activity, so bad, my personal experience, NetApp have lots of bugs and the
good part is they keep working on them.
While in Hitachi training they were more focusing more
on the cache part that means in Hitachi storage you can do lot of cache
modification, like you can set the cache size as per your application and the
data is first written to the cache and then to the disk, so that if there is any
disk failure the cache data will get copied to the flash memory and the content
can remain there for infinite time (means until you get recovered from your
power failure).
Even there is one more features in Hitachi unified
storage that you can fix size of the block of greater size, like every storage
divides the data into their some default block size like 4kb or etc. and then
store it in disk, but in Hitachi you can increase the block striping size of
greater size also, but these all activity should only be done when you get the
recommendation from the Hitachi technical team.
Now striping the block of bigger size is really a
fantastic feature and it really improves the performance, so by all this good
features you can see that Hitachi is more concentrated on performance and that
really good and best things of Hitachi storage apart from this basic
installation of Hitachi is quite easier compared to NetApp and EMC and then the
part replacement is also quite easier than the NetApp and EMC , well for the
part replacement you don’t to apply your extra brain just go and remove the
faulty part that’s all .
But still if you see that today’s storage world is
talking about deduplication and automatic tearing, which is still not there in
Hitachi storage, and these features will be soon launched in coming version.
Below are the file module specifications:
Below is HUS block storage specification:
Now in HUS unified storage you have to buy the
block level storage and file level then only it is unified, so when you say
that u wan Hitachi unified you will get block and file both.
Well I have not deeply explained the features of
Hitachi storage, because still I need to work in this product and by working on
any product you can easily understand about it, so in future I will be writing
some more blogs on Hitachi product.
