Re: RAID 0 risky ?
On Wed, 2002-03-20 at 01:03, Dave Watkins wrote: replicate the data somehow. RAID 5 obviously does the least replication while still keeping fault tolerance, although it does cost a small amount of computing power (not a problem if you have a RAID card) Some RAID cards are substantially slower at RAID 5 than 0/1/0+1. The 3ware ATA RAID boards are excellent, for example, except at RAID 5. They now produce a couple of boards with more CPU power or different ASICs, or whatever, to make up for this shortfall. But they are more expensive. IIRC the 7x10 series is quite slow at RAID 5, but the 7x50 series improved upon this greatly. My source is www.storagereview.com, though, I do not use any of their newer RAID 5 boards. -- Jeff S Wheeler [EMAIL PROTECTED] Software DevelopmentFive Elements, Inc http://www.five-elements.com/~jsw/ -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: RAID 0 risky ?
Some RAID cards are substantially slower at RAID 5 than 0/1/0+1. The 3ware ATA RAID boards are excellent, for example, except at RAID 5. They now produce a couple of boards with more CPU power or different ASICs, or whatever, to make up for this shortfall. But they are more expensive. IIRC the 7x10 series is quite slow at RAID 5, but the 7x50 series improved upon this greatly. My source is www.storagereview.com, though, I do not use any of their newer RAID 5 boards. I hear the latest 3ware 7.4 firmware upgrade has increased the performance of RAID5 quite a bit by optimizing the read/write alogrithm. Not that I've upgraded any of our servers... we're still on 7.3.2 (or whatever the last 7.3.x was). We'll wait till maybe 7.4.1 or until no one complaints of bugs anymore. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
RAID 0 risky ?
Is RAID 0 that risky anymore for data storage (IMAP mail files) ? I figure that under normal wear and tear a drive should last about 5 years. Does this sound right ? I have 3 IBM SCSI 18GB drives. With RAID 0, I get 51.5GB of storage space. With RAID 5, I only get 37 GB of space with 20% wasted overhead. RAID 0 and RAID 1 are less work for the disk volume than RAID 5. So in an ideal world, volumes with RAID 0 or RAID 1 will last longer than volumes in RAID 5. Thus, it would be less risk to use RAID 0 or better RAID 1 than RAID 5. - Ted Knab -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: RAID 0 risky ?
Thedore Knab wrote: Is RAID 0 that risky anymore for data storage (IMAP mail files) ? I figure that under normal wear and tear a drive should last about 5 years. Does this sound right ? I have 3 IBM SCSI 18GB drives. With RAID 0, I get 51.5GB of storage space. With RAID 5, I only get 37 GB of space with 20% wasted overhead. RAID 0 and RAID 1 are less work for the disk volume than RAID 5. So in an ideal world, volumes with RAID 0 or RAID 1 will last longer than volumes in RAID 5. No. In RAID 5, you can lose one drive, and still keep running. In RAID 0 (striped), the loss of one drive will kill your volume. Let's say the odds are 1 in 10 of a drive dying in a particular year. If you have 5 drives in RAID 0, you have a 50% chance of your volume crashing (well, that's probably not exactly right, but my statistics abilities are a little rusty). If you have 5 drives in RAID 5, you have a 50% chance of _one_ drive dying. I'm not sure that there's significantly less work for RAID 0 than RAID 5. RAID 1 will definately have less reads on any particular drive than the other two (approzimately 50% will go to one disk, 50% to the other), but will have greater writes (100% of writes will affect both disks on RAID 1, it's possible some writes will not affect every disk on RAID 5, I think). Since you're looking at IMAP mail files, the data is probably critical... too critical to trust in a single drive failure. You're probably most concerned with read performance (since users will notice lag in reading email... deleting messages can plod away just fine, writing to the mail files is done by the MDA). Take a look at how much space you need, or are likely to need in the future. If you need a lot of space I'd go with RAID 5. If you want to really push the read performance, buy another drive and go RAID 1. I'd stay away from RAID 0 unless it's fairly non-critical data, and if you really need the throughput. An example I can think of would be something like a web cache. Thus, it would be less risk to use RAID 0 or better RAID 1 than RAID 5. Absolutely not. RAID 0 is the highest risk. RAID 0 is actually higher risk than a single drive. --Rich _ Rich Puhek ETN Systems Inc. _ -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
