Time Machine and RAID
hey all,
i was just reading about RAID (i was totally ignorant to it, and am now a tiny bit less ignorant to it!) and was interested in its use to backup, as well as performance purposes. i currently use a 60gig USB drive as a permanent mirror or my internal harddrive although i do this manually using Synk (http://www.decimus.net) it certainly seems that RAID would be able to provide the facility much more conveniently however i'm planning to buy an imac as soon as possible and so the effort required wouldn't be worthwhile in the meantime
anyway, my main point is, i was very interested in Time Machine for providing my backups if i upgrade to leopard but i was wondering what everyone thought were the relative merits to using time machine or using RAID. i like the idea of having a complete mirror or my internal drive, but restoring is hardly convenient. time machine looks very slick but i'm unsure if it's really a solution against drive failure
so i guess i would most like to initiate a discussion about time machine vs. RAID for backup! sorry about the inelegant post, there, hope i got my points across!
i was just reading about RAID (i was totally ignorant to it, and am now a tiny bit less ignorant to it!) and was interested in its use to backup, as well as performance purposes. i currently use a 60gig USB drive as a permanent mirror or my internal harddrive although i do this manually using Synk (http://www.decimus.net) it certainly seems that RAID would be able to provide the facility much more conveniently however i'm planning to buy an imac as soon as possible and so the effort required wouldn't be worthwhile in the meantime
anyway, my main point is, i was very interested in Time Machine for providing my backups if i upgrade to leopard but i was wondering what everyone thought were the relative merits to using time machine or using RAID. i like the idea of having a complete mirror or my internal drive, but restoring is hardly convenient. time machine looks very slick but i'm unsure if it's really a solution against drive failure
so i guess i would most like to initiate a discussion about time machine vs. RAID for backup! sorry about the inelegant post, there, hope i got my points across!
Comments
One interesting point is that one who judiciously uses RAID 0 for the speed can mitigate their risk (one drive loss means all data loss) by setting up a Time Machine drive with plentiful snapshots. Thus if your RAID 0 set goes down you do have the ability to replace the corrupt/crashed drive and pull your Time Machine data back on.
i'm so ignorant of RAID i would be glad to hear any suggestions of how a home use might make use of it. at the moment i have a 250gb and a 60gb drive used externally, but as and when i get a new imac i was considering doing a user upgrade of the internal drive (250gb?) with something like a 500gb drive. i'd then have 2*250gb drives and 1*60gb drives going spare. i was wondering about buying a firewire 800 RAID case for those. would that be useful? i do a lot of music production and would like to put a lot of libraries of samples on the hard drive. zfs interests me, especially in the sense that i could make that all one big storage pool.
so i wonder if the 60gb disc would be useful for time machine. the apple site says it backs up "everything" but would that include all system files, or just user folders? i wonder how much disc space you would need to use with it relative to the size of your drive.
Mac OS X supports software RAID 1. That would require two disks of the same size, and would make one disk an exact copy of the other. This would allow you to painless carry on if one of those disks died, because you have an exact copy of it.
Time Machine would do more than that. It would allow you to not only have a back-up of what's on your hard drive today, but also back up whatever you deleted, incase you delete something by accident. It also does limited version control (so you can see what a document or folder looked like last week). It would require more hard drive space externally than internally (since you're fully backing up your drive and then some).
Leopard won't have ZFS.
Mac OS X supports software RAID 1. That would require two disks of the same size, and would make one disk an exact copy of the other. This would allow you to painless carry on if one of those disks died, because you have an exact copy of it.
Time Machine would do more than that. It would allow you to not only have a back-up of what's on your hard drive today, but also back up whatever you deleted, incase you delete something by accident. It also does limited version control (so you can see what a document or folder looked like last week). It would require more hard drive space externally than internally (since you're fully backing up your drive and then some).
righty ho. certainly sounds a bit like that. so os x doesn't support raid for performance enhancement? shame. would a RAID case be able to support this in hardware if the OS can't? i've been looking at RAID cases. and it does seem like there is a significant lack of zfs news with regard to leopard. again, shame. looks like i'm gonna have a bunch of disks on my desk at this rate!
righty ho. certainly sounds a bit like that. so os x doesn't support raid for performance enhancement? shame. would a RAID case be able to support this in hardware if the OS can't? i've been looking at RAID cases. and it does seem like there is a significant lack of zfs news with regard to leopard. again, shame. looks like i'm gonna have a bunch of disks on my desk at this rate!
OS X supports RAID 0, which is performance-enhancing. I didn't mention it because it's not redundant, and actually puts your data at more risk (since you lose the data if either drive fails)
If you have a hardware case that has an internal RAID controller, or if you install a supported PCIe RAID controller, then you will be fine. However, make sure any hardware is Mac-compatible.
Additionally, the server version of OS X (which you can buy and install on any Mac) can do software RAID 5 or software RAID 10. There may be some fancy magical way to do that on regular Mac OS X, but I haven't heard of it, and if there were a way, it wouldn't be for the faint-hearted, since it'd be a kernel extension or a hacked driver.