>From my experience (YMMV), most RAID controllers will NOT redistribute the >existing data/files onto the newly added drives. So, if you have a (3) drive >RAID5 your file exists on all three drives, as does the parity data. If you >add (2) drives, your original files will not be on the new drives. New files >WILL use all (5) drives. IMHO it's best to backup the data (twice), create a >new volume on the new RAID, and restore the data. That said, maybe >better/newer RAID controllers will redistribute / balance existing data across >all drives in the array - I don't know for sure. Either way, backup your data >- twice! And make sure it can be restored! Just because the backup app SAYS >it's OK, it's NOT OK until it can be successfully restored!
Also, if you go from (7) drives to (3), your I/O may suffer. Newer faster drives MAY make up the difference, or make up enough of it that it won't impact your client. Just be aware this is a potential issue. Generally speaking more spindles = more I/O's / sec. G -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Almberg Sent: Monday, July 26, 2010 3:31 PM To: Chuck Swiger Cc: [email protected] Subject: Re: 1 file system, 2 drives? > If you have hardware controller with RAID capabilities, using native RAID is > better, otherwise look towards gvinum or maybe ccd; see also: > I've just been reading up on RAID in my Absolute FreeBSD book, and it occurs to me that my client has a SCSI RAID drive chassis that he is using stupidly... It's a 14 bay drive, and he's currently got seven 32G drives stuck in it, configured with RAID-0. This is the original 200G drive I was talking about. It's a few years old. Over the next few years, this guy is going to need lots of storage for his videos. After a bit of reading, I'm wondering if the best idea might be to toss out those 32G drives and replace them with 3 big (say, 300G) drives configured with RAID-5. It sounds to me like a RAID-5 array can be expanded by adding new drives. QUESTION: is expansion normally a matter of just plugging in a new drive? Is the new drive automatically grafted onto the old drives? Or do you have to go through a process like, backing up the data, plugging in the new drive, reformatting the expanded array of drives, and restoring the data. I don't know the brand/model of the RAID drive chassis, but the client thinks it can be switched to use RAID 5. I'm waiting for the technical details, but assuming it can handle RAID-5 for now. Thanks: John _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[email protected]" <font size="1"> <div style='border:none;border-bottom:double windowtext 2.25pt;padding:0in 0in 1.0pt 0in'> </div> "This email is intended to be reviewed by only the intended recipient and may contain information that is privileged and/or confidential. If you are not the intended recipient, you are hereby notified that any review, use, dissemination, disclosure or copying of this email and its attachments, if any, is strictly prohibited. If you have received this email in error, please immediately notify the sender by return email and delete this email from your system." </font> _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[email protected]"
