Reliability Manager Interview Questions
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Reliability Manager interview questions shared by candidates
How many bits is the access flags of a file?
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I'd say 9, since the three bits you have mentioned have to be multiplied by the three user groups (owner, group, others). rwxrwxrwx Less
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9 is closest, but you may have forgotten about 3 more bits used for special access; setgid, setuid, and the sticky bit. Which makes 12. They are part of the inode that describes the file permissions and file type - the last 4 are the file type but not related to permissions, which is what the question asked. Less
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Traditional Unix permissions are broken down into: so answer is 3 read (r) write (w) execute file/access directory (x) Each of those is stored as a bit, where 1 means permitted and 0 means not permitted. Less
How would you count the # of words in a text ?
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In bash tr ' ' '\n'|fgrep -c "word" in python list.count('word') perl: #!/usr/bin/perl my $count = 0; open(FH, './dumbfile'); foreach ( ) { split / /; if ($_ =~ /word/) { $count++; } } print "Found $count instances of word\n"; So yeah. Less
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In bash tr ' ' '\n'|fgrep -c "word" in python: with open('./dumbfile', 'r') as f: count = 0 for line in f.readlines(): for item in line.split(): if item == 'word': count +=1 print "%d instances of word" % count perl: #!/usr/bin/perl my $count = 0; open(FH, './dumbfile'); foreach ( ) { @new = split / /, $_; foreach(@new) { if ($_ =~ /word/) { $count++; } } } print "Found $count instances of word\n"; Less
How many computers would it take to run gmail.
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Assume that gmail has 2 bln of users (there are 3 bln internet users around the world and almost every internet user around the world has a gmail account). Assume that average size of mailbox is 500Mb (I've worked at many email services and know what I'm saying). 2 bln by 500Mb is 1000pb (petabytes). If gmail stores each email 3 times (2 times is a good choice, but since users' mailboxes are scattered around the storage cluster then 2 collapsed hard disks at the same moment could result in some data lost while the possibility of 3 hard disk have collapsed in the different data centers at the same time is negligibly low) then total is 3000pb. But I'm completely sure that gmail has deduplication and gmail has text parts of emails zipped. The first measure can save around 50% of space (the most of the mail store - it's attachments, and attachments are usually sent by person, so an attachment appears twice - in an inbox folder and in a sent folder). The second measure can save around 20% of space (this is the approximate total size of all text parts of mailings that could loose their weight by times). So 3000Pb are reduced by 70% to again 1000Pb. A 36x4Tb storage server has a 144Tb capacity. 1000Pb divide by 144Tb is about 7000. Why is it 36x4Tb? Because 36 is as far as I know economically feasible maximum number of disks per server. And 4Tb is economically feasible maximum disk size. I mean here that the more disks per server the less is the cost of the server other-than-disk parts per byte of storage but to the limit after that other-than-disk parts become more expensive. So is about the disk size - the bigger the disk size the cheaper is the byte stored on it, but to the limit of 4Tb. Of course gmail is not only storage service. There are also web services, smtp, imap, pop3, MX, antispam and so on. All of these services just process data and they don't have to store anything large (maybe there are some databases negligible compared to the email storage to store user credentials for example). A service does not necessarily needs a separate server. And storage servers luckily have a plenty of CPU time and some memory. So, the storage server's CPU time, memory and small portion of the disk could be used for data processing and for some small databases needed to web services, smtp, pop3, imap and so on. Google would not be Google, if they used a lot of additional servers for the life of the email system, except the email storage servers. That's why the correct answer is 7000 servers. Less
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These sorts of questions don't have answers. The real answer is to think out loud about what would be required in terms of bandwidth, storage, computing power, etc. for all of the different elements: receiving, sending, website, spam filtering, addressbook lookup, ... Less
1. Complexity... are you kidding me? Is this a college grad course? Most questions will be based around data structure and algorithms; even though this have nothing to do with day to day job (I asked what a detailed typical day was during process) 2. DRBD and HA/heartbeat linux; interviewer was way outside of his depth and didn't fully understand clustering. Refrained from correcting him when he started down wrong path with questions. 3. write a script on the fly; type of questions. Again; nothing to do with actual operations. make a script do this to a string of words make a script do this to groups and users accounts on linux system etc... On a live google hangout; no vim, no emacs... cannot use your function library you've built over the years; exactly how NO ONE programs anymore. 4. Not one troubleshooting question 5. Not a single Past action review question.
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Impossible to answer most questions; they want you to study for the interview and learn how to survive their obscene process. News for Google; you're not that amazing... Interview is about both parties deciding they want to work for each other. Insulting people with 10-20 years of accomplishments with a interview process tailored for fresh college grads is bit skewed. Expectation is that you spend 2-3 weeks learning about the questions they will ask and having pre-canned scripts to write on fly. Less
How do you provide permission for everyone to read a file in current directory name "apple" at the unix prompt.
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chmod a+r apple The a stands for "all", the + for "add", and the r for "read".
My background in the field, as well as why I thought I would be a good fit for the position. I didn't think I would be a good fit since it wasn't the position I applied for, so my resume had been passed to him.
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I told him the position he was asking about wasn't the one I had applied to, but explained what my talents and strengths were, and he agreed they were something Google could definitely use and I would be a good fit for other positions he know were open. Except the next day I was told there were no such openings, thank you, goodbye. Less
What are the major observability capabilities needed for an organization?
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Explained logs, metrics, APM
Explain the process of 1-click deployment.
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Pipeline process using Jenkins, Puppet and Python.