neil4933
asked on
Is RAID10 the best?
I am have heard that RAID 10 is now the best and recommended by MS for everything. My understanding is that RAID10 is essentially, two pairs of mirrors, thus requiring 4 drives.
Is this true? I know the MS previously recommended RAID5?
Is RAID10 now the best for any sort of applcation, regardless of it's behaviour.
Is this true? I know the MS previously recommended RAID5?
Is RAID10 now the best for any sort of applcation, regardless of it's behaviour.
raid 10 tends to give the best overall performance for reading and writing data - but you lose half your capacity.
some raid configurations can be faster at reading and slower at writing data which may have its application.
for 99 out of 100 people Raid 10 is the choice.
check out..
http://www.petri.co.il/raid-levels-comparison-guide.htm
http://en.wikipedia.org/wiki/Standard_RAID_levels
and http://www.midwestdatarecovery.com/raid-array-types.html
for more details
some raid configurations can be faster at reading and slower at writing data which may have its application.
for 99 out of 100 people Raid 10 is the choice.
check out..
http://www.petri.co.il/raid-levels-comparison-guide.htm
http://en.wikipedia.org/wiki/Standard_RAID_levels
and http://www.midwestdatarecovery.com/raid-array-types.html
for more details
I wish it was that simple. It really depends on the workload and your requirements.
(The following assumes a SAN array or quality RAID controller):
For example, a RAID 5 set of 5 drives will have superior write performance for a 256kB write. It will have similar read performance to a 4 drive RAID 10 set. The RAID 10 set will outperform the RAID 5 set for small block random I/O.
Like I say: it depends.
(The following assumes a SAN array or quality RAID controller):
For example, a RAID 5 set of 5 drives will have superior write performance for a 256kB write. It will have similar read performance to a 4 drive RAID 10 set. The RAID 10 set will outperform the RAID 5 set for small block random I/O.
Like I say: it depends.
Perhaps you could ask whether RAID 10 is superior to RAID 5 when one of the disks has failed. RAID 5 is often virtually unusable with a failed disk until rebuilding is complete.
>RAID 5 is often virtually unusable with a failed disk until rebuilding is complete.
Not an absolute.
You will take a performance hit,but if you have more than 3 spindles,that is not written in stone.
You also would need to factor in whether or not the RAID controller has a co processor too.
Good RAID controllers bypass having to use CPU resources(although I have heard it argued that using a core on a CPU alleviates this.) .
None the less it does eat up CPU cycles one way or the other.
I've had disks fail and rebuild in more than one system,and production was just fine and usable
I could see if you were running RAID 5 software with 3 SATA TB hardrives and it becoming slow as they rebuild.
You also take a chance that if you lose a 2nd drive,your data is hosed.
Quite troubling considering that your bit rate error on larger drives grows exponentially the larger they become ,and if you hit a double bit parity error,ugh!
Speaking of RAID,it appears as if MS has fired a shot over the bow of NetApp and it's ilk.with something in Server 2012/W8 called Storage Spaces.
We'll see.
Not an absolute.
You will take a performance hit,but if you have more than 3 spindles,that is not written in stone.
You also would need to factor in whether or not the RAID controller has a co processor too.
Good RAID controllers bypass having to use CPU resources(although I have heard it argued that using a core on a CPU alleviates this.) .
None the less it does eat up CPU cycles one way or the other.
I've had disks fail and rebuild in more than one system,and production was just fine and usable
I could see if you were running RAID 5 software with 3 SATA TB hardrives and it becoming slow as they rebuild.
You also take a chance that if you lose a 2nd drive,your data is hosed.
Quite troubling considering that your bit rate error on larger drives grows exponentially the larger they become ,and if you hit a double bit parity error,ugh!
Speaking of RAID,it appears as if MS has fired a shot over the bow of NetApp and it's ilk.with something in Server 2012/W8 called Storage Spaces.
We'll see.
ASKER
Thanks everyone...
So let's take Exchange as an example -
Exchange logs are heavy on sequential writes
Exchange DB is heavy on random reads
UP until now, the thinking has been to put behaviour like the logs on a RAID1, and behaviour like the DB on a RAID5.
Why does RAID10 suddenly seem like the best, that is what I'm trying to get at? Are we saying that because disks are now so cheap, RAID10 is viable?
So let's take Exchange as an example -
Exchange logs are heavy on sequential writes
Exchange DB is heavy on random reads
UP until now, the thinking has been to put behaviour like the logs on a RAID1, and behaviour like the DB on a RAID5.
Why does RAID10 suddenly seem like the best, that is what I'm trying to get at? Are we saying that because disks are now so cheap, RAID10 is viable?
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The best RAID type depends on your application and requirements. For a given workload, RAID 10 often needs fewer drives than a RAID 5 set because of write penalties, but RAID 5 gives you more space for a given number of drives.
So - the answer is: it depends. :-)