Thanks Olivier and Scot for your inputs! Another data point I would like to share is that VMs will be built in Azure Cloud with Azure Managed Storage and Locally redundant storage (LRS) option with a remote DR as well.
LVM or ZFS would still be a good option to allow easy storage/disk management like add, resize or remove disks while PostgreSQL services are up? Is equal data distribution a challenge on LVM/ZFS disks? Thanks Amit On Tue, Jan 23, 2024 at 9:49 AM Scot Kreienkamp < scot.kreienk...@la-z-boy.com> wrote: > El lun, 22 ene 2024 18:44, Amit Sharma <amitpg...@gmail.com> escribió: > > Hi, > > > > We are building new VMs for PostgreSQL v15 on RHEL 8.x For a large > database of 15TB-20TB. > > > > I would like to know from the experts that is it a good idea to create > LVMs to manage storage for the database? > > > > Or are there any other better options/tools for disk groups in PostgreSQL, > similar to ASM in Oracle? > > > > Thanks > > Amit > > > > Simple question that requires a somewhat more complex answer. There are > actually 3 metrics to consider: > > > > 1) Capacity > > Your database doesn't fit on a single disk, so you need to distribute your > data across several disks. LVM would indeed be an option (as well as ZFS or > RAID disk arrays) > > > > 2) Safety > > If you loose 1 disk, your data is at risk, as you're likely to loose all > tables partially loaded on that disk. LVM is still an option as long as it > is configured on a RAID array. ZFS can do that natively. > > > > 3) Performance > > Oracle ADM ensures performance by automatically controlling the > distribution of the tables. I would need to see on a real case how it is > actually done. For sure, LVM and ZFS won't have this type of granularity. > > > > On the other hand, you can distribute your data in table partitions to > help this distribution. It is not automatic but will surely help you to > distribute your workload. > > > > > > As he is building VM’s I’m assuming the hardware level has all the > redundancy for RAID/ZFS/etc. If that is the case then you don’t want to > run RAID/ZFS/etc on top of that, let the hardware do its thing. If my > assumption is wrong then ignore everything I’m saying. > > > > One thing I found that helps with speed of reads/writes… you can spread > your read/write load across multiple SCSI controllers/disks using LVM. For > example, I’m assuming VMWare which allows 4 SCSI controllers. Set the OS > disk on SCSI controller 0, then spread your database disks in sets of 3 > across SCSI controllers 1-3, IE 3 disks of 5TB each, one on each SCSI > controller. Then when you create your LVM partition specify the option to > stripe it with 3 stripes. That gives you a setup where you are > multiplexing reads/writes across all 3 SCSI controllers and disks instead > of bottlenecking them all through 1 SCSI controller and disk at a time. > > *Scot Kreienkamp | Applications Infrastructure Architect | La-Z-Boy > Corporate* > One La-Z-Boy Drive | Monroe, Michigan 48162 | ( (734) 384-6403 | | ) > 1-734-915-1444 | * scot.kreienk...@la-z-boy.com > www.la-z-boy.com | facebook.com/lazboy | twitter.com/lazboy | > youtube.com/lazboy > [image: Smaller LZB Only Logo for Sign.png] > > This message is intended only for the individual or entity to which it is > addressed. It may contain privileged, confidential information which is > exempt from disclosure under applicable laws. If you are not the intended > recipient, you are strictly prohibited from disseminating or distributing > this information (other than to the intended recipient) or copying this > information. If you have received this communication in error, please > notify us immediately by e-mail or by telephone at the above number. Thank > you. >
