Dnia 2011-09-09, pią o godzinie 14:34 +0200, David Brown pisze: > On 09/09/2011 12:48, Michał Sawicz wrote: > > Hi all, given the configuration below: > > * 8 x 1TB HDDs > > * 2 x 2TB HDDs > > > > On which I currently have: > > * (10 x 1TB) RAID6 - persistent storage > > * (2 x 1TB) system / temporary storage etc. > > > > By this do you mean that you have 8 x 1TB drives with a 1 TB partition > on each, and 2 x 2T drives with 2 x 1TB partition on each? So that the > two big disks are shared with both raids? Yes, that wasn't like that before, but that's a result of exchanging two 1TB drives to 2TB ones. > > I want to replace the 1TB drives for 2TB ones on an as-needed basis, > > what strategy would you recommend? > > This sounds like you are thinking that you can replace a single disk in > your RAID6 array and get more storage - changing 10 x 1 TB raid6 = 8TB > into 9 x 1TB + 1 x 2TB raid6 = 9 TB. It doesn't work like that. You > will have to replace /all/ your 1 TB devices with 2 TB devices (and move > the second raid off the two existing 2TB devices) - all members of the > raid6 must be the same size. Actually no, I know how RAIDs work, so the three schemes I described below account for that. > To help you plan your upgrades, it is also useful to know your > partitioning scheme (for example, do you use LVM?), whether you have the > space to put lots more drives in the system or must do it one drive at a > time, whether you can take the system off-line during the process, and > whether you need to do the upgrade quickly or can spend a week or so at > it (some of these are conflicting requirements). No LVM here. The most important - big RAID6 - is a single partition. The remaining 2 x 1TB on the big drives are split into RAID1 for boot, RAID10 for root, RAID0 for temporary storage and swap space. I can temporarily put more drives in there. I can take it off-line for some periods and I can do the upgrade over an extended period of time. > Before you think about upgrading, however, make sure you have a solid > backup. Then make sure you have a backup of that backup - and a plan > for how to restore everything if something goes horribly wrong. Yeah... I plan to rely on RAID's redundancy by moving data around, growing / shrinking the filesystems and then shuffling the HDDs. I know that's asking for trouble, but I haven't yet found a place to rent 8TBs of storage for a week... And that's worked for me in the past, btw. Twice, even, IIRC. -- Michał (Saviq) Sawicz <michal@xxxxxxxxxx>
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