[Gluster-users] Advice for setup: SW RAID 6 vs JBOD
emayoral at arsys.es
Thu Jun 6 17:20:51 UTC 2019
Yes to the 10 GB NICS (they are already on the servers).
Nice idea with the SSDs, but I do not have a HW RAID card on these
servers or the possibility to get / install one.
What I do have is an extra SSD disk per server which I plan to use as
LVM cache for the bricks (Maybe just 1 disk, maybe 2 with SW RAID 1). I
still need to test how LVM / gluster are going to handle the failure of
the cache disk.
On 6/6/19 19:07, Vincent Royer wrote:
> What if you have two fast 2TB SSDs per server in hardware RAID 1, 3
> hosts in replica 3. Dual 10gb enterprise nics. This would end up
> being a single 2TB volume, correct? Seems like that would offer great
> speed and have pretty decent survivability.
> On Wed, Jun 5, 2019 at 11:54 PM Hu Bert <revirii at googlemail.com
> <mailto:revirii at googlemail.com>> wrote:
> Good morning,
> my comment won't help you directly, but i thought i'd send it
> 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.
> Am Mi., 5. Juni 2019 um 11:33 Uhr schrieb Eduardo Mayoral
> <emayoral at arsys.es <mailto:emayoral at arsys.es>>:
> > 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
> > as cache or similar to improve performance, since it is already
> > 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
> > not sure if that makes any difference.
> > The amount of data I have to store there is currently 20 TB,
> > 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 at arsys.es <mailto:emayoral at arsys.es> - +34 941 620 105 -
> ext 2153
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Eduardo Mayoral Jimeno
Systems engineer, platform department. Arsys Internet.
emayoral at arsys.es - +34 941 620 105 - ext 2153
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