Hi, I know that one of the most fundamental principles when designing Exchange storage is to put the Exchange transaction logs on RAID1 arrays due to its write-intensive nature. I know that RAID5 is discouraged due to its extra overhead on writes. But given the large amounts of disk read/write cache that's available on current storage systems, and their fast transfer speeds of 2 or 4 Gbps, I'm wondering if anyone out there has been putting their transaction logs on RAID5 arrays without problems. I'm asking because I'm going to be moving my Exchange data from one storage system to another. While the transaction logs are on RAID1 on the current system, I need to put them on RAID5 on the new system due to limited disk space and the need to maximize the capacity of the remaining disks. I know this is exactly the type of situation that an Exchange admin should do everything to avoid, but I really don't have any other options, because we're going to be getting rid of the current storage and the new storage is maxed out, with no more disk space, so I need to do this to fit in the Exchange data. My environment is as follows - Exchange 2003 Enterprise SP2 Windows 2003 Enterprise SP2 1800 mailboxes 15 databases spread across 4 storage groups (1.6 TB total) new storage: IBM DS4700 (mid-range storage system) Thanks in advance for any insight or guidance....

I dont think its so much its bad to have RAID5 but its more can the disks handle the IOPS you will be generating and the performance impact of that.Mark Morowczynski|MCSE 2003:Messaging, Security|MCITP:ES, SA|MCTS:Windows Mobile Admin|Security+|http://almostdailytech.com

Hi, For transaction logs drive we recommend RAID 1 or RAID 0+1 and databases RAID5 array. From Article : Tuning Exchange Server 2003 Performance.http://technet.microsoft.com/en-us/library/bb124129(EXCHG.65).aspx In summary, the following are your best guidelines for configuring mailbox servers: 1, Create a RAID1 partition for Windows and Exchange binary files.2, Put the pagefile on a separate RAID1 spindle. For mailbox servers, you should never put the pagefile on a non-RAID partition because the loss of the volume causes the server to stop.3, Create one dedicated fault-tolerant partition for each storage group for the transaction logs (for example, RAID1 or RAID 0+1). A two-disk RAID1 partition should yield approximately 300 sequential write I/O operations a second. This capacity should be more than sufficient for a busy five-database storage group. 4, Create at least one fault-tolerant partition for your databases. If you have only one array, put all databases on this array. If you have multiple arrays, use one array for each storage group (databases only). Besides the answers, I would like to provide you with some tips regarding retrieve the disk space, for your consideration: 1. Transaction logs can be truncated by performing backup for the Information Store. Every successful backup will truncate all the transaction logs it has archived, and will usually free up more than 95% of the disk space the transaction logs has occupied. So I suggest you schedule a Backup plan for the Information Store. For example, a full backup at the weekend, and daily incremental backup on weekdays. 2. For database size concern, I recommend you try the offline defragment on your server, which will retrieve some disk space. Thanks Allen