I would be implementing exchange 2013 soon and we are planning to   8 x 1200GB 10k SAS disks (5TB avaiable space), So i am just curious to know if RAID 5 is good option for Exchange 2013 dat

RAID 1 and 5 is better choice, personally I have been using RAID 1-5 only in all of my projects.
For log volumes, RAID-1 or RAID-1/0 is the recommended RAID configuration.

RAID-5 configurations, including variations such as RAID-50 and RAID-51, should have no more than 7 disks per array group and array controller high-priority scrubbing and surface scanning en

Hi,

Raid 5 is no longer recommended, especially for large disk arrays (See Dell recommendation).

Interested in more background? Here are links to an argument on Raid 5 and 6:

• Raid 5
• Raid 6

The basic reasoning is the high risk of rebuild failure makes it inadvisable (Which is why Gulab recommended that even with 50 or 51 to prioritize scrubbing and scanning - reduces rebuild failure chance due to read error).

Cheers,
Fred

Exchange 2013 storage configuration options

https://technet.microsoft.com/en-us/library/ee832792(v=exchg.150).aspx

If you have budget, my opinion is Raid 10 is the best option for better performance and availability.If you have less than 300 Users Raid 5 is enough. My recomendation is add hot spare disk for safety purpose.

I have seen you have 8 disk and pretty good writing speed 10K

1 disk= 1200 GB

8 * 1200 = 9600 GB

If you configure RAID 10

you will get = 4800 useful

Another suggestion is configure Multi RAID

Raid 5 for data base // 6 TB for useful 1.2 TB for parity "1 drive allow to fail" 

or

RAID 6 // 4.8 TB useful 2.4 TB for parity " 2 drive allow to fail ,Less Tension than RAID 5"

Raid 1 for Logs      //    1.2 TB for logs

• Edited by Joby M Chacko 18 hours 49 minutes ago Add Raid 6 info

If you have budget, my opinion is Raid 10 is the best option for better performance and availability.If you have less than 300 Users Raid 5 is enough. My recomendation is add hot spare disk for safety purpose.

I have seen you have 8 disk and pretty good writing speed 10K

1 disk= 1200 GB

8 * 1200 = 9600 GB

If you configure RAID 10

you will get = 4800 useful

Another suggestion is configure Multi RAID

Raid 5 for data base // 6 TB for useful 1.2 TB for parity "1 drive allow to fail" 

or

RAID 6 // 4.8 TB useful 2.4 TB for parity " 2 drive allow to fail ,Less Tension than RAID 5"

Raid 1 for Logs      //    1.2 TB for logs

• Edited by Joby M Chacko Wednesday, February 04, 2015 5:00 PM Add Raid 6 info

Thanks everyone for the input, so below is how my hardware will look for exchange 2013 Mailbox server role for 8000 Users. CAS Role Hardware sizing is different which i will post if required in discussion.

==========

Total 3 MBX servers and each server will have same Hardware config.

========================

So if i have to go with Mailbox database 5 TB usable i should opt for Raid 6 or Raid 5 with additonal Array controller split of 4 x 1200 GB on each Array and can increase the disk if required in future.

Hi,

Question: Why do you need 5TB?

Considering both performance and reliability, going with Raid 10 is superior to Raid 5 or 6. Raid 10 leaves you with 4.8TB. Assuming equal distribution of Mailboxes across all 3 MBX, that's ...

• ~1.84366 GB per Mailbox
• ~1.47493 GB per Mailbox if you reserve 20% of total space for emergency use
• 1266 GB Free space, assuming 20% reserve that's not factored into that total and a 1GB size limit for mailboxes

Frankly, if you show me a company that averages for more than 1GB on mailboxes, I'll show you a company that needs to reconsider its retention policies and archiving strategy.

I seriously advice against taking the performance hit of Raid 5 when compared to Raid 10 (or Raid 50, which offers better Space utilization (in your case 75%, instead of the 50% of R10, which would have you hitting the 5TB limit you appear to be working under) but significantly lower performance when degraded).

Cheers,

Hi BR,

as mentioned, the problem with Raid 5 is Performance and reliability. You can improve both with Raid 50 (which is basically a Raid 0 across two Raid 5s). Since R50 is superior to R5 in every aspect while providing the same storage ...

Here's a quick comparison table:

Raid   Storage  Performance   Reliability   Performance (Degraded)
R10     4.8TB       High             Awesome     High
R50     7.2TB       High               High           Low

From that point on it's a priorities question. Do you need the extra storage or do you want the superior performance during a defect? IOps might be better in Exchange 2013, but a degraded Raid50 drops to the speed of a single disk on the degraded R5 (a 33% drop in performance) - you're users are still likely to notice if that happens during business hours.

Our own priorities where I work at would say Raid 10 (We archive mails away and severely limit mailbox size). Can't tell you what your priorities are.

Cheers,
Fred

Hi BR,

good luck with management. If you need some aid with arguments, measuring current storage loads may be helpful:

# Get statistics for all mailboxes
$MBS = Get-MailboxDatabase | Get-MailboxStatistics

# Measure size of objects in each mailbox and return total size and Average Size
$mbs | Measure-Object TotalItemSize -Sum -Average

# Grab list of top Mailbox sizes
$mbs | Sort-Object TotalItemSize -Descending | Select-Object -First 80

I don't have an Exchange ready at hand where I am just now, so I can't validate this, but it should work just fine. This way you can see just how much storage your mailboxes use (and thus estimate what storage you'll probably need in the foreseeable future) and detect any really problematical mailboxes.

Seriously though - if your total storage requirements even approach 8TB for 8000 Mailboxes, I'd say it's high time to consider tougher Mailbox retention policies, stricter maximum mail sizes (Especially for internal mails) and a practical archiving strategy. You don't need to maintain that much dead data on your most expensive storage (factoring in maintenance, administration, backup, ... costs).

Cheers,
Fred

Our Plan is to spread 8000 Mailbox's across 3 box in active site, out of which only 800 Mailbox will have mailbox quota of 1 GB, and remaining users 7200 will have 200 MB of mailbox quota, so plan is to have

total 12 Mailbox database out of which 3 our dedicated database of users whose mailbox quota will be 1Gb and reaming 9 MBX database will have 7200 users whose mailbox quota will be 200 MB and each server will have 8x1.2 TB raid 5 or Raid 50 so usable space would be ~6.5 TB per server which will have 12 DB (4 Active and 8 Passive). So we are expecting the 3 MBX DB which is dedicated for 1 Gb quota will start from aproxx 266 GB and start growing there onward, there other 9 DB which will hold 7200 users and have 200 mb quota will start growing from 156 GB each.