## Messed up my partitioning installation, now windows can’t boot. What do I do?

I have windows 7 installed. I guess I deleted a partition that didn’t have system written on to free up some space for root , /home and swap. But somehow I can’t revert back to its original state and the installation even failed. Now I can’t boot my windows and I guess all my files are gone too. I still have windows recovering system but it doesn’t want to do anything. Anyone knows how to recover the files?

## postgresql zabbix partitioning autovaccum causes locking

I have a Zabbix database on a postgresql server that got quite huge (~1TB of Data on disk)
The Zabbix housekeeper (A Process of removing old data from the tables) starts to run for 18h+
So I start looking around and found that possibility of table partitoning. (So far so good) I user this Script to enable partitioning.

But now exactly on midnight, Zabbix stops inserting Data into the database, right when a new partitioned table should get created.

I found out that when I kill the running autovacuum process (mostly on the table history or history_uint) via SELECT pg_cancel_backend(12345); the zabbix server can finish his insert as some locks go away and continue normal operation again.
Unfortunately, I only figured this out 7 Hours later, in the morning. no i have ow 2 days of missing monitoring data from 00:00 – 07:00.

I Understood that the Vauum process is needed in order to free up transaction ID’s so I should NOT do this every day.

My question is now: Is partitioning a bad idea? (at least in a already running setup?) Should I have started with partitioned tables all along? Therefore, should I throw out all our monitoring data, and insert it again into correctly partitioned tables? (huge amount of work…) Should I Disable Autovacuum on those partitioned tables? because I guess that the issue comes from a global lock on all schemas .public and .partitions

The final goal should be to reduce the DB load of the system so it performs better.
By Enabling Partitioning I was able to reduce the runtime of the housekeeper down to a few minutes/seconds via disabling the housekeeping of History and trend data. But its no positive result if the monitoring stops working after midnight…

Additional Information: The Hardware is Oversized quite a lot (All SSD, , and performing only OK(ish). I guess because I don’t really know what knobs to tweak I better don’t touch them at all.

## Dual booting Windows 10 and Ubuntu on 128 GB SSD and 1TB HDD drive. What is the best partitioning choice?

I want to install Ubuntu alongside Windows 10 but I am not sure how to partition my drives.

My SSD drive (where Windows 10 is on) has around 50 GB free space and my 1TB HDD has around 600 GB free space. This HDD already contains some other files. Also I have 8GB RAM.

I am doubting between different kind of partitions and even after a couple of hours of research I cannot decide what would be the best set-up. Here are my current options:

1. All SSD. I would partition 40GB on the SSD drive and go /(20GB), swap(8GB), /home(12GB) — Does Windows have enough space?, Can I access my HDD drive files?, Do I even need the swap in this case?

2. All HDD. Since I have more than enough space, it would look something like /(50-60GB), swap(8GB), /home(50-60GB) — What is the downside of this non-SSD installation (speed and computing power)?

3. A Combination of SSD and HDD. I would use 40 GB SSD for /(32GB)& swap(8GB). My files (which require no precious SSD space) would be partitioned on the HDD /home(50-60GB). — Can I still access my other HDD drive files?

4. … Any other suggestions?

Currently, my OS starts in a matter of seconds and the same for all of the applications. Although the 2nd option sounds preferable to me (I will never experience memory shortage), I don’t know how much this will effect the speed and stuff…

As you might have expected, I am new to all of this so It’s very possible I am making some rookie mistakes here. My apologies for that.

## How to clean up partitions and use manual partitioning during installation?

In the past I successfully installed Ubuntu 18.04.1 LTS alongside Windows and was able to prioritize it on Windows Boot Manager in order to boot immediately when starting my laptop. Then one day it disappeared from the list and started booting back into Windows. I prioritized booting option via the boot manager however, it kept booting into Windows directly.

I re-installed Ubuntu and the same issue came about however, this time I went through the motions of installation then re-booting went directly to Windows. Like the Ubuntu installation never happened.

I have cleared out Windows and am happy to get rid of it completely so I would like to manually clean-up the partitions, select a partition, and install Ubuntu 18.04.1 LTS entirely.

The partition list looks as follows. Any advice on how to achieve this once and for all?

Thank you in advance! parition list The partition lit is actually longer than the one linked however, I can only upload one on the main post. I will try add the second in the comment section.

## Is Edmonds’ Matroid partitioning algorithm optimal w.r.t lexicographical order?

We all know that, given a matroid $$(E, \mathcal{I})$$, Edmonds’ Matroid partitioning algorithm will result in a tuple of $$E$$-covering, pairwise-disjoint independent sets $$(I_1, …, I_k)$$ with optimal (smallest) $$k$$.

Assume the sizes of $$I_j$$ are decreasingly sorted: $$|I_1| \ge \; … \; \ge |I_k|$$.

My question: Is $$(|I_1|, …, |I_k|)$$ optimal (largest) w.r.t the lexicographical order of the lexicon $$\mathbb{Z^+} = \{ 1 < 2 < 3 < … \}$$.

If this is NOT the case, is there any algorithm finding a tuple of $$E$$-covering, pairwise-disjoint independent sets $$(I_1, …, I_k)$$ with the optimality of $$(|I_1|, …, |I_k|)$$ ? Potentially it may sacrifice the optimality of $$k$$.

## Bootcamp – Stuck on “Partitioning Disk…”

When attempting to add a Windows 10 (April 2018, build 1803) partition to my 2019 iMac, I get stuck on “Partitioning disk…” perpetually.

When I look at Disk Utility, the OSXRESERVED and BOOTCAMP partitions appear:

My iMac is running the latest stable release of macOS, 10.14.5 (18F132). Is there a known bug/solution to this problem?

## Balanced $\epsilon$-separated partitioning by a hyperplane

Suppose we have $$m$$ points in $$R^n$$ and $$\epsilon>0$$ is a given constant. How can we find a hyperplane that the number of points that are $$\epsilon$$-close to it is minimum, with the constraint that it partitions the points to two sets of equal size. More formally, if the hyperplane is parametrized by $$u^\top x = b$$, in which $$||u||_2=1$$ is the unit vector orthogonal to the hyperplane. The constraint is that the number of points that is in the halfspace $$u^\top x is equal to the number of points in $$u^\top x. Among all the hyperplanes that satisfy this constraint, we want to minimize over points that are in the space $$|u^\top x – b|\le \epsilon$$. Is there a relatively fast algorithm (quadratic or cubic at most) algorithm that solves this efficiently?

## Ubuntu 18.04 Desktop installation using preseed freezing after partitioning

I’m trying to automate ubuntu 18.04 LTS Desktop installation using seed file, but unfortunately I’m unable to proceed futher after patitioning step while installation, as the window got hang.

Even I copy – paste entire “https://help.ubuntu.com/lts/installation-guide/example-preseed.txt” still the same problem

Below is the current configuration

d-i debian-installer/locale string en_US d-i passwd/user-fullname string test host d-i passwd/username string test d-i passwd/user-password password ubuntutest d-i passwd/user-password-again password ubuntutest d-i partman-auto/method string lvm d-i partman-lvm/device_remove_lvm boolean true d-i partman-lvm/confirm boolean true d-i partman-lvm/confirm_nooverwrite boolean true tasksel tasksel/first multiselect ubuntu-desktop d-i pkgsel/include string ssh vim build-essential   d-i pkgsel/upgrade select none 

I just mention the seed files in the boot params as auto url=http://192.168.56.101/test.cfg

Here I’m testing on Virtual box.

## Partitioning a graph with specific constraints

We have an exercise where we need to find the partitions G[V1] and G[V2] of a graph G=(V,E), that fulfill the following constraints. We also know that there exists at least one partition that fulfills these constraints:

• |V1| – |V2| = 0 or 1 (V1 and V2 have the same amount of nodes or V1 contains one node more that V2)
• either
• [case A] all nodes in V1 have edges to all nodes in V2
• [case B] all nodes in V1 have no edges to any node in V2

We had a few ideas to find those partitions via divide-and-conquer involving the degrees of each node to differentiate between case A and B. If we find any node v with degree(v) < |V2| then there is a partition with case B, otherwise if we find a node v with degree(v) > |V1| then there is a partition that fulfills case A. However other than that we have been stuck and extendind or other ideas ended in a dead end.

How do we find those partitions? I’d like to not be given the answer but only a pointer to find a easy algorithm for the problem.

## MongoDB replica set quorum config (network partitioning behaviour)

I use mongodb 4.0.10. I want to establish a quorum for a cluster of one primary node and two secondary nodes as written here. When the number of nodes is less than the quorum, 3 nodes in my case, cluster goes to readonly (no election).

I`ve tried to set priority of two nodes to 0, in this case if primary goes down, there is no election, but if one of secondaries goes down, old primary still exists.

According to MongoDB docs terminology is it possible to set a replica set Fault Tolerance to zero? It means that if any of cluster nodes goes down new primary will not be elected.