Aaron, I've seen this discussed before, but I couldn't find a reference in my bookmarks. I did find this in google. http://www.fiveanddime.net/ss/swap.htm
I have never tried the "pri=x" option listed in that web page, but it makes sense. Basically, you can setup multiple swap partitions, and place them on different drives, and the kernel will give you a RAID0-like performance edge on them. There is no obvious or good way to get a RAID1 or 5 like system where you have multiple stores of same data. (And, I'm not even sure if that makes sense for swap) I guess you'd have to answer the question "Do I absolutely need my swap to survive if a drive should fail?" before trying to do a RAID1/5 setup. I think I can live without failover swap space, but I'm not running anything close to mission critical. Ultimately, if you're really concerned about performance, turn off swap altogether. (It would be nice if you could request that certain users or processes could fall through on a memory allocation request that required swap access, but others (lower perms) would get an Out Of Memory error.) Anyway, if you ever get around to trying out those options, let us know what you find. --dk On 07Jun2004 10:17AM (-0700), Aaron Lopez wrote: > Linux gurus, > I got a question for you guys. In a high availability production linux > system with a RAID 1 or RAID 5 install, is it generally better to setup > your swap partition(s) to be non-RAID or do you want your swap to be > redundant as well? > From an I/O perspective, if you are writing to swap you don't want the > overhead of RAID 1/RAID 5 to slow you down (even though reads would be > fast). I can also see the I/O advantage of have a swap partition on each > of the drives but not in the RAID itself. > Now for the argument the other way. If high availability is more of a > concern than I/O, shouldn't the swap partition be put in a RAID. > Some vendors like Penguin Computing claim that putting swap in a RAID 5 > using 6 IDE drives will yield horrible performance. Does that sound > right? Do the writes of a RAID 5 create that much overhead for swap? > > > Aaron Lopez > PerMedics Inc. System Administrator > 909.558.8155 > [email protected] > > _______________________________________________ > 909linux mailing list > [email protected] > http://909linux.org/cgi-bin/mailman/listinfo/909linux -- /* david kaiser (NO SPAM/UCE) pubkey=1C8DCC8D begin e-mail decoder */ main() {int j=-1;char t[]="gndlvhuCfgn1frp\r";while(t[j]!='\r'){putchar(t[++j]-3);}0;}
