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  • Reblogging: My experience with using cp to copy a lot of files 432 millions, 39 TB

    One morning I was notified that a disk had failed. No big deal, this happens
    now and then. I called Dell and next day I had a replacement disk. While
    rebuilding, the replacement disk failed, and in the meantime another disk had
    also failed. Now Dell’s support wisely suggested that I did not just replace
    the failed disks as the array may have been punctured. Apparently, and as I
    understand it, disks are only reported as failed when they have sufficiently
    many bad blocks, and if you’re unlucky you can lose data if 3 corresponding
    blocks on different disks become bad within a short time, so that the RAID
    controller does not have a chance to detect the failures, recalculate the data
    from the parity, and store it somewhere else. So even though only two drives
    flashed red, data might have been lost.

    Having almost used up the capacity we decided to order another storage
    enclosure, copy the files from the old one to the new one, and then get the old
    one into a trustworthy state and use it to extend the total capacity. Normally
    I’d have copied/moved the files at block-level (eg. using dd or pvmove), but
    suspecting bad blocks, I went for a file-level copy because then I’d know which
    files contained the bad blocks. I browsed the net for other peoples’ experience
    with copying many files and quickly decided that cp would do the job nicely.
    Knowing that preserving the hardlinks would require bookkeeping of which files
    have already been copied I also ordered 8 GB more RAM for the server and
    configured more swap space.

    When the new hardware had arrived I started the copying, and at first it
    proceeded nicely at around 300-400 MB/s as measured with iotop. After a while
    the speed decreased considerably, because most of the time was spent creating
    hardlinks, and it takes time to ensure that the filesystem is always in a
    consistent state. We use XFS, and we were probably suffering for not disabling
    write barriers which can be done when the RAID controller has a write cache
    with a trustworthy battery backup. As expected, the memory usage of the cp
    command increased steadily and was soon in the gigabytes.

    For more visit: My experience with using cp to copy a lot of files 432 millions, 39 TB.

  • Olacabs, First time and Last Time

    Olacabs, First time and Last Time

    Olacabs , First time and Last Time

    Olacabs

    On 8Th July I booked a Cab from Olacabs at 11.01 PM from My residence towards CSIA Airport and Return scheduled at 6.45 AM.

    I had done the booking from the site and received email confirmation after 8 minutes with the CRN number: 7177728.

    Normally in such services of Booking, scheduling, pickups, etc. SMS is critical, however I did not receive an SMS confirmation. That made me worry at that exact moment, hence I sent a quick Question through their WebEngage widget on right side.

    I got a confirmation that my “Question” was received by Olacabs via automated reply from WebEngage.

    OlaCabs WebEngage Reply
    OlaCabs WebEngage Auto-Reply

    However there has been no reply to that till date.

    Not receiving a quick response I called up Olacabs at around 12.30 AM and asked told them that I haven’t received the SMS, can you provide me the Car  details and driver contact info ?

    The support rep Rahul, he ignored the “did not receive SMS part” informed that I will get a call 30 mins before scheduled time.

    I was relieved, assuming i would get a call.

    But, then. Early morning I was waiting for the call from Olacabs, the call did not come till 6.30 AM.

    I immediately called up Olacabs to ask for status, to my surprise. They said the Booking was cancelled.

    Which I never Did. Why would I ? When I needed the service ?

    I told the rep that I did NOT cancel the booking who did ? and what now. He told me to hangup and he will revert within 5 minutes.

    I hung-up, but I was growing impatient as we had to go to pick up a relative from airport. I called them again and asked them I did not cancel my booking, then who cancelled it from your side ?

    He told me

    The booking was automatically cancelled by system because your phone number was incorrect as it was starting with 9198XXXXXX.

    It struck me immediately, I had used Auto Fill on Google Chrome to fill in the details (unfortunately I used auto-fill for the first time), and I got to know what would have happened exactly.

    I asked him if there is any nearby cab right now there was none and I hung up the call, I was angry and could not even escalate the issue then as I had to manage another transport to get there.

    I did not enter the number incorrectly, in fact, I did not enter it at all. I used a simple tool which a ton of people use over the web today, its Auto-Fill.

    What happened was the phone number field at Olacabs site is usual 10 Digit field. However, when Auto Fill inserted the number it inserted with the country code 91, hence the last 2 digits of my no did not go into the field. My mistake was that I trusted Auto-fill to the fullest, and did not re-check the detail.

    However, I was concerned when I did not receive the SMS confirmation even after receiving the email of the booking and hence had called up support and told them that i did not receive SMS.

    If people at Olacabs know that they cancel a booking due to an incorrect number, why did the support executive not confirm the number with me when on call? When i explicitly stated that i did not receive the SMS ?

    This is critical as they were having 2 modes to communicate with me Email and SMS, I would have found the issue well before if they had provided the phone number in the email, however they did not. The email had everything except the phone number, which is the single criteria they use to confirm or cancel bookings.

    Ola Cabs Booking Confirmation
    Booking Confirmation – No Number

    In short what I have to say is that Olacabs has failed for me, really badly.

    I had high expectations for Olacabs, because they have demonstrated being passionate about their service. I could not expect such issues from a service provider, which had taken steps beyond normal to pacify an upset customer. This was reported on SocialSamosa too. Heres the link :

    http://www.socialsamosa.com/2013/12/socially-active-brand-turned-frustrated-customer-into-advocate/

    May be My Expectation of Olacab being customer-centric was Wrong ?

    Because i am not such a significant influencer on Social Media as was in above case and that the question i submitted was Private so no Ola was not expecting any damage nor publicity for fixing.

    If Olacabs really cared for customers, not just Influencers It would have replied to my question long back not waiting for me to write this blog post.

    How could this have been avoided ?

    1. Me checking the Phone number while using auto-fill or manually. Agree.
    2. Minimum expectation from Ola Cabs support was that the exec took utmost care when customer said “I did not receive SMS” considering it a Red flag and fixing the issue then and there.
    3. Providing the Phone number along-with the other Booking details in the Email confirmation

    The most easiest, they could have set up the Email Confirmation as such it provides All Details and most importantly the phone number as they just consider phone number to cancel or validate the booking. There are other providers who are doing this, nothing new.

    taxiforsure Booking Confirmation
    Taxi For Sure- Providing Essential Info in Confirmation Email IMG Source: www.tanay.co.in

    Its been 4 Days since I left them that question, and they haven’t responded. I am sure its lying unattended in someone’s Inbox who would delete it someday.

    Will I book again with Ola Cabs ?

    Probably not… Not again

    ​​

  • Elon Musk, our patent’s will not come in your way Tesla Motors

    Elon Musk, our patent’s will not come in your way Tesla Motors

    Elon Musk CEO of Tesla Motors and SpaceX just announced that Tesla Motors which holds at least 133 Patents will be allowed for  use by anyone with fair intentions.

    Tesla will not initiate patent lawsuits against anyone who, in good faith. wants to use our technology.

    In times when innovation is Rare and Costly, Elon Musk has set a extraordinary example by letting this happen and he has a greater vision for doing this, simply say. He wants all Or any of the competitors/manufacturers to use the technology that they have developed by intellect, sweat and money.

    Here’s a Pic of the wall that held the patents

    The Tesla Patent Wall at HQ, now set free

    A good Close-up

    The Tesla Motors Patent Wall
    The Tesla Motors Patent Wall

    The most humbling thing about Elon Musk is that he is completely Okay with other competitors sharing the pie of the market, as he bravely accepts that they alone can not satisfy the needs for good future cars which have a positive impact on earth.

    I strongly believe that Elon and the stakeholders in Tesla Motors are equally to be thanked in this decision, as in todays capitalist environment this is a brave move.

    Lets just see if other’s take some learning.

    Image Source: Steve Jurvetson

    Source: All Our Patent Are Belong To You | Blog | Tesla Motors.

  • Should You Hire a Programmer or DIY? | Vinicius Vacanti

    You have the next big idea but don’t have a strong technical background and you don’t have a great technical co-founder lined up. Sadly, that represents over 95% of potential entrepreneurs out there and it’s a very frustrating experience

     

    Read full article here:

    Should You Hire a Programmer or DIY? | Vinicius Vacanti.