On Sun, 06 May 2012 19:27:59 +0000, Ramon Hofer wrote: > On Sun, 06 May 2012 18:10:41 +0000, Camaleón wrote:
>>>>> You have drives of the same size in your raid. >>>> >>>> Yes, that's a limitation coming from the hardware raid controller. >>> >>> Isn't this limitation coming from the raid idea itself? >> >> Well, no, software raid does not impose such limit because you can work >> with partitions instead. >> >> In hardware raid I can use, for example, a 120 GiB disk with 200 GiB >> disk and make a RAID 1 level but the volume will be of just 120 GiB. (I >> lose 80 GiB. of space in addition to the 50% for the RAID 1 :-/). > > But you can't build a linux software raid with a 100 GB and a 200 GB > disk and then have 150 GB? Of course. But still you can use the remainded (non-raided) space for another non-vital usage (small secondary backup/data partition, a boot partition, for swap...). Although this is not recommended, it can be useful in some scenarios. >>> You can't use disks with different sizes in a linux raid neither? Only >>> if you divide them into same sized partitions? >> >> Yes, you can! In both, hardware raid and software raid. Linux raid even >> allows to use different disks (SATA+PATA) while I don't think it's >> recommended becasue of the bus speeds. > > What I mean was the space difference is lost in either ways? For the raided space, yes, but still you can "redistribute" the disk better. >>> So you directly let the array rebuild to see if the disk is still ok? >> >> Exactly, rebuilding starts automatically (that's a default setting, it >> is configurable). And rebuiling always ends with no problem with the >> same disk that went down. In my case this happens (→ the array going >> down) because of the poor quality hard disks that were not tagged as >> "enterprise" nor to be used for RAID layouts (they were "plain" Seagate >> Barracuda). I did not build the system so I have to care about that for >> the next time. > > I'd like using green drives for this system. So low power consumption is > a thing I try keep low. And until now they worked well (one false > positive in two years is ok) Remember that a raided system is more exigent than a non-raided one. If one of that "green" disks which is part of a raid level is put in stand- by/sleep mode and does not respond as quickly as mdadm expects, the raid manager can think the disk is lost/missing and will mark that disk as "failed" (or will give I/O erros...), forcing a rebuild, etc... :-/ Those "green" disks can be good for using them as stand-alone devices for user backup/archiving but not for 24/365 nor a NAS nor something that requires quick access and fast speeds such a raid. >>> I have an i3 in that machine and 4 GB RAM. I'll see if this is enough >>> when I have to rebuild all the arrays :-) >> >> Mmm... I'd consider adding more RAM (at least 8 GB) though I would >> prefer 16-32 GB) you have to feed your little "big monster" :-) > > That much :-O For RAM you never-ever get enough :-) > Ok, RAM is quite cheap and it shouldn't affect power consumption with in > comparison to >20 hard disks. Exactly, your system will be happier and you won't have to worry in increasing it for a near future (~5 years). My motto is "always fill your system with the maximum amount of RAM, as much as you can afford", you won't regret. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/jo8mji$e2o$2...@dough.gmane.org