schford Posted October 15, 2015 Share Posted October 15, 2015 So I am just about ready to finally finish my new build and move the data off my current 25TB RAID array. I wanted to ask what the best way to do this was? I wondered if I was better moving it all off without Parity active (if this is possible) so as notto slow the initial write speed down, then turn on Parity and let it build the parity up overnight? Would really appreciate any recommendations. Thanks Stuart Quote Link to comment
gubbgnutten Posted October 15, 2015 Share Posted October 15, 2015 If you copy (not move) the data from your current array to your new build, sure. Writing data to a server without parity protection is quite fast. [*]Set up the new server with data disks, but don't assign parity [*]Start array on new server [*]Copy data from old server [*]Stop array on new server [*]Assign parity [*]Start array on new server [*]Wait for rebuild [*]Verify data witch checksums if possible [*]Do whatever you want with the old server. Keep in mind that backups are nice, though Quote Link to comment
schford Posted October 15, 2015 Author Share Posted October 15, 2015 Thanks :-) Makes Perfect sense....I will be re purposing the drives from the existing raid array - but don't need them straight away... Great simple to follow walk through! Cheers Stuart Quote Link to comment
luvmich Posted October 15, 2015 Share Posted October 15, 2015 The other thing you can do is turn on "Turbo writes". Type this in at a console or SSH "mdcmd set md_write_method 1". That speeds my writes upto 100Meg/sec. This way you can have your parity and move stuff to the new box. Quote Link to comment
schford Posted October 15, 2015 Author Share Posted October 15, 2015 Interesting - what does it do and how is it different to the default settings? Thanks Stuart Quote Link to comment
dgaschk Posted October 16, 2015 Share Posted October 16, 2015 It changes the parity update algorithm so that writes are faster but all array disks are accessed during a write. This trades power consumption for improved write performance. The standard method only accesses the target data drive and the parity drive, albeit each one twice. Quote Link to comment
ALNiKO Posted October 16, 2015 Share Posted October 16, 2015 How do I move data from old server to a new one with only 1 unRAID Pro license? If I pull out a data drive from an old server, will I be able to connect it to a new server and copy files from it? Quote Link to comment
schford Posted October 18, 2015 Author Share Posted October 18, 2015 It changes the parity update algorithm so that writes are faster but all array disks are accessed during a write. This trades power consumption for improved write performance. The standard method only accesses the target data drive and the parity drive, albeit each one twice. How does this increase performance by so much - this world is very different to my old HArdware RAID 5 setup! Thanks in advance :-) Quote Link to comment
garycase Posted October 18, 2015 Share Posted October 18, 2015 It changes the parity update algorithm so that writes are faster but all array disks are accessed during a write. This trades power consumption for improved write performance. The standard method only accesses the target data drive and the parity drive, albeit each one twice. How does this increase performance by so much - this world is very different to my old HArdware RAID 5 setup! Thanks in advance :-) A standard write to a protected array requires 4 disk I/O operations. First, the sector being written to and the corresponding parity sector are read; then the new data is written to the data drive, and based on the changes in the bits from what WAS there, parity is updated and written to the parity disk. A "turbo write" skips the initial read of the data disk and parity disk. It simply reads all of the other data disks; then writes the new data and the computed parity. So basically it writes the new data while reading all the other data disks; then writes the parity sector. This eliminates the initial read of the data disk ... saving one full rotation of the disk. This can make writes significantly faster, as long as all of the disks are spun up. Note that for the normal process, only the disk being written to and the parity disk need to be spun up. A "turbo write' requires that all disks are spinning. Quote Link to comment
schford Posted October 18, 2015 Author Share Posted October 18, 2015 Thanks so much for explaining Gary - I am sure I will click with it all soon :-) It does lead me on to another questions - What to have in my Disk Settings? I notice that out of the box Enable Auto Start is no, Default Spin Down Delay is never etc etc I am guessing that both form a Heat / Power & Longevity point of view we wont the drives to sleep - any pointers for some good settings to work form? Cheers Stuart Quote Link to comment
garycase Posted October 19, 2015 Share Posted October 19, 2015 Auto Start simply means you want the array to start when you boot the system -- most folks probably turn this on; but if you prefer to look at the Web GUI after you boot and before the array is started, then leave it off. Default spin down is just what it says ... if you want the drives to spin 24/7 you can leave it at "never" => this will provide the quickest response when you access the array, but the drives will always be spinning. I suspect most folks prefer to have unused drives spun down. What to set them to depends on your usage pattern ... if you tend to use them throughout the day, you may want this set fairly high (a couple hours) so they're not likely to spin down in-between uses; if you don't mind a short delay while a drive (or drives) spin up, then you can make it relatively short (30-45 minutes). Quote Link to comment
switchman Posted October 19, 2015 Share Posted October 19, 2015 How do I move data from old server to a new one with only 1 unRAID Pro license? If I pull out a data drive from an old server, will I be able to connect it to a new server and copy files from it? Purchase a new key or move all you drives into the new system. Then upgrade the drives in place to the new drives. Quote Link to comment
trurl Posted October 19, 2015 Share Posted October 19, 2015 How do I move data from old server to a new one with only 1 unRAID Pro license? If I pull out a data drive from an old server, will I be able to connect it to a new server and copy files from it? Purchase a new key or move all you drives into the new system. Then upgrade the drives in place to the new drives. The data drives can be put in a new server if you do New Config. If you don't do New Config and instead try to add them as new data drives unRAID will clear them. If you don't want them as array drives in the new server, but instead just want to attach them temporarily while you copy the data from them to new drives, you can use the Unassigned Devices plugin. Quote Link to comment
schford Posted October 22, 2015 Author Share Posted October 22, 2015 The other thing you can do is turn on "Turbo writes". Type this in at a console or SSH "mdcmd set md_write_method 1". That speeds my writes upto 100Meg/sec. This way you can have your parity and move stuff to the new box. How would one turn this off after turning it on if we wanted to go back to the vanilla way of working. Cheers Stuart Quote Link to comment
trurl Posted October 22, 2015 Share Posted October 22, 2015 The other thing you can do is turn on "Turbo writes". Type this in at a console or SSH "mdcmd set md_write_method 1". That speeds my writes upto 100Meg/sec. This way you can have your parity and move stuff to the new box. How would one turn this off after turning it on if we wanted to go back to the vanilla way of working. Cheers Stuart mdcmd set md_write_method 0 Quote Link to comment
schford Posted October 25, 2015 Author Share Posted October 25, 2015 thank you :-) Quote Link to comment
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