I need some help deciding what is the best way to increase our storage capacity.
Currently we have 2 MSA60s each with 12 SATA drives, originally all 750GB but some have been replaced with 1TB. The arrays are set up as in the following images taken from the ACU: Physical-View-1.tiff
Four of the arrays are RAID 5, one is RAID 6.
The data is backed up to tape at least annually, with differentials each week.
The arrays are now on average 85% full of data, and growing slowly.
Q1: If the 4 drives in Array A are replaced by 4 x 2TB drives, can this new array indeed be 6TB with RAID 5, with 3 logical drives of 2TB each? I admit to being really confused about the 2TB limit. The OS is Windows 2008 R2. I had previously understood that the RAID configuration applied to the logical drives, but now believe it applies to the SATA Array itself. Is this correct?
As there is no dedicated IT person on site, the priority is on redundancy and reliability. Performance is not so important, as this is mainly archive data with only a handful of users, despite its 10TB size.
Q2: Is it better to stay with SATA, or is SAS a better option for new drives? I believe they can be "mixed" in this configuration - is that true, and is it advisable?
Q3: It is becoming difficult to find unused drive letters for the network shares corresponding to these 5 arrays. Is there any way to extend the range beyond A to Z for these shares (like Excel uses AA, AB, AC, ...)?
Q4: What is the correct procedure for removing and re-instating the disks of one of the arrays, to maintain their integrity? I know about maintaining their sequence, but am uncertain in what order to power down the MSA60 and also the host Server, and vice versa. When we transferred the MSA60s from one server to another, one of the arrays was lost, and had to be recreated from the backup tapes.
Q5: Is it better to stay with RAID 5 or RAID 6, or change to RAID 1 or RAID 10? We have always used RAID 5 and found it to be successful, with an occasional disk failure every year or so. I have seen scathing remarks abot this configuration, but so far cannot agree with them. We use HP Midline drives.
I realise this is a lot of loosely related questions, but hope somebody can rescue me from ignorance!