Your comment actually helps me more than you think, one of the main doubts I have is whether I go for JOBD with replica 3 or SW RAID 6 with replica2 + arbitrer. Before reading your email I was leaning more towards JOBD, as reconstruction of a moderately big RAID 6 with mdadm can be painful too. Now I see a reconstruct is going to be painful either way... For the record, the workload I am going to migrate is currently 18,314,445 MB and 34,752,784 inodes (which is not exactly the same as files, but let's use that for a rough estimate), for an average file size of about 539 KB per file. Thanks a lot for your time and insights! On 6/6/19 8:53, Hu Bert wrote: > Good morning, > > my comment won't help you directly, but i thought i'd send it anyway... > > Our first glusterfs setup had 3 servers withs 4 disks=bricks (10TB, > JBOD) each. Was running fine in the beginning, but then 1 disk failed. > The following heal took ~1 month, with a bad performance (quite high > IO). Shortly after the heal hat finished another disk failed -> same > problems again. Not funny. > > For our new system we decided to use 3 servers with 10 disks (10 TB) > each, but now the 10 disks in a SW RAID 10 (well, we split the 10 > disks into 2 SW RAID 10, each of them is a brick, we have 2 gluster > volumes). A lot of disk space "wasted", with this type of SW RAID and > a replicate 3 setup, but we wanted to avoid the "healing takes a long > time with bad performance" problems. Now mdadm takes care of > replicating data, glusterfs should always see "good" bricks. > > And the decision may depend on what kind of data you have. Many small > files, like tens of millions? Or not that much, but bigger files? I > once watched a video (i think it was this one: > https://www.youtube.com/watch?v=61HDVwttNYI). Recommendation there: > RAID 6 or 10 for small files, for big files... well, already 2 years > "old" ;-) > > As i said, this won't help you directly. You have to identify what's > most important for your scenario; as you said, high performance is not > an issue - if this is true even when you have slight performance > issues after a disk fail then ok. My experience so far: the bigger and > slower the disks are and the more data you have -> healing will hurt > -> try to avoid this. If the disks are small and fast (SSDs), healing > will be faster -> JBOD is an option. > > > hth, > Hubert > > Am Mi., 5. Juni 2019 um 11:33 Uhr schrieb Eduardo Mayoral <emayoral@xxxxxxxx>: >> Hi, >> >> I am looking into a new gluster deployment to replace an ancient one. >> >> For this deployment I will be using some repurposed servers I >> already have in stock. The disk specs are 12 * 3 TB SATA disks. No HW >> RAID controller. They also have some SSD which would be nice to leverage >> as cache or similar to improve performance, since it is already there. >> Advice on how to leverage the SSDs would be greatly appreciated. >> >> One of the design choices I have to make is using 3 nodes for a >> replica-3 with JBOD, or using 2 nodes with a replica-2 and using SW RAID >> 6 for the disks, maybe adding a 3rd node with a smaller amount of disk >> as metadata node for the replica set. I would love to hear advice on the >> pros and cons of each setup from the gluster experts. >> >> The data will be accessed from 4 to 6 systems with native gluster, >> not sure if that makes any difference. >> >> The amount of data I have to store there is currently 20 TB, with >> moderate growth. iops are quite low so high performance is not an issue. >> The data will fit in any of the two setups. >> >> Thanks in advance for your advice! >> >> -- >> Eduardo Mayoral Jimeno >> Systems engineer, platform department. Arsys Internet. >> emayoral@xxxxxxxx - +34 941 620 105 - ext 2153 >> >> >> _______________________________________________ >> Gluster-users mailing list >> Gluster-users@xxxxxxxxxxx >> https://lists.gluster.org/mailman/listinfo/gluster-users -- Eduardo Mayoral Jimeno Systems engineer, platform department. Arsys Internet. emayoral@xxxxxxxx - +34 941 620 105 - ext 2153 _______________________________________________ Gluster-users mailing list Gluster-users@xxxxxxxxxxx https://lists.gluster.org/mailman/listinfo/gluster-users
